fix(userspace/libscap): fix build without USE_ZLIB macro.

[FedeDP]

What type of PR is this?

/kind cleanup

Any specific area of the project related to this PR?

/area libscap

Does this PR require a change in the driver versions?

What this PR does / why we need it:

We always tried to support building libscap without USE_ZLIB macro (that is hard-defined in scap/settings.h).

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FedeDP

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[FedeDP]

/milestone 0.19.0

[github-actions]

Perf diff from master - unit tests

     9.26%     +1.59%  [.] sinsp_parser::reset
     9.04%     -1.20%  [.] sinsp::next
     1.20%     +0.78%  [.] std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release
     0.61%     +0.62%  [.] sinsp_filter_check::parse_field_name
     1.39%     +0.60%  [.] std::_Hashtable<long, std::pair<long const, std::shared_ptr<sinsp_threadinfo> >, std::allocator<std::pair<long const, std::shared_ptr<sinsp_threadinfo> > >, std::__detail::_Select1st, std::equal_to<long>, std::hash<long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_before_node
     0.73%     -0.56%  [.] std::_Hashtable<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, libsinsp::state::dynamic_struct::field_info>, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, libsinsp::state::dynamic_struct::field_info> >, std::__detail::_Select1st, std::equal_to<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::hash<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, false, true> >::_M_find_before_node
     5.56%     +0.47%  [.] sinsp_evt::get_type
     0.78%     +0.42%  [.] std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>
     5.46%     -0.41%  [.] next
     0.38%     +0.39%  [.] sinsp_cgroup::lookup_cgroups

Heap diff from master - unit tests

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Heap diff from master - scap file

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Benchmarks diff from master

Comparing gbench_data.json to /root/actions-runner/_work/libs/libs/build/gbench_data.json
Benchmark                                                         Time             CPU      Time Old      Time New       CPU Old       CPU New
----------------------------------------------------------------------------------------------------------------------------------------------
BM_sinsp_split_mean                                            +0.0182         +0.0182           147           150           147           150
BM_sinsp_split_median                                          +0.0207         +0.0207           147           150           147           150
BM_sinsp_split_stddev                                          +1.6515         +1.6533             0             1             0             1
BM_sinsp_split_cv                                              +1.6041         +1.6060             0             0             0             0
BM_sinsp_concatenate_paths_relative_path_mean                  +0.0280         +0.0280            57            58            57            58
BM_sinsp_concatenate_paths_relative_path_median                +0.0013         +0.0013            57            57            57            57
BM_sinsp_concatenate_paths_relative_path_stddev               +13.8404        +13.8566             0             2             0             2
BM_sinsp_concatenate_paths_relative_path_cv                   +13.4368        +13.4526             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_mean                     -0.0380         -0.0380            25            24            25            24
BM_sinsp_concatenate_paths_empty_path_median                   -0.0318         -0.0318            25            24            25            24
BM_sinsp_concatenate_paths_empty_path_stddev                   -0.8325         -0.8322             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_cv                       -0.8259         -0.8256             0             0             0             0
BM_sinsp_concatenate_paths_absolute_path_mean                  +0.1287         +0.1287            57            64            57            64
BM_sinsp_concatenate_paths_absolute_path_median                +0.1312         +0.1312            56            64            56            64
BM_sinsp_concatenate_paths_absolute_path_stddev                -0.5374         -0.5372             1             0             1             0
BM_sinsp_concatenate_paths_absolute_path_cv                    -0.5902         -0.5900             0             0             0             0
BM_sinsp_split_container_image_mean                            +0.0044         +0.0044           402           404           402           404
BM_sinsp_split_container_image_median                          +0.0013         +0.0013           403           403           403           403
BM_sinsp_split_container_image_stddev                          -0.3552         -0.3544             3             2             3             2
BM_sinsp_split_container_image_cv                              -0.3581         -0.3572             0             0             0             0

[github-actions]

X64 kernel testing matrix

KERNEL	CMAKE-CONFIGURE	KMOD BUILD	KMOD SCAP-OPEN	BPF-PROBE BUILD	BPF-PROBE SCAP-OPEN	MODERN-BPF SCAP-OPEN
amazonlinux2-4.19	🟢	🟢	🟢	🟢	🟢	🟡
amazonlinux2-5.10	🟢	🟢	🟢	🟢	🟢	🟢
amazonlinux2-5.15	🟢	🟢	🟢	🟢	🟢	🟢
amazonlinux2-5.4	🟢	🟢	🟢	🟢	🟢	🟡
amazonlinux2022-5.15	🟢	🟢	🟢	🟢	🟢	🟢
amazonlinux2023-6.1	🟢	🟢	🟢	🟢	🟢	🟢
archlinux-6.0	🟢	🟢	🟢	🟢	🟢	🟢
archlinux-6.7	🟢	🟢	🟢	🟢	🟢	🟢
centos-3.10	🟢	🟢	🟢	🟡	🟡	🟡
centos-4.18	🟢	🟢	🟢	🟢	🟢	🟢
centos-5.14	🟢	🟢	🟢	🟢	🟢	🟢
fedora-5.17	🟢	🟢	🟢	🟢	🟢	🟢
fedora-5.8	🟢	🟢	🟢	🟢	🟢	🟢
fedora-6.2	🟢	🟢	🟢	🟢	🟢	🟢
oraclelinux-3.10	🟢	🟢	🟢	🟡	🟡	🟡
oraclelinux-4.14	🟢	🟢	🟢	🟢	🟢	🟡
oraclelinux-5.15	🟢	🟢	🟢	🟢	🟢	🟢
oraclelinux-5.4	🟢	🟢	🟢	🟢	🟢	🟡
ubuntu-4.15	🟢	🟢	🟢	🟢	🟢	🟡
ubuntu-5.8	🟢	🟢	🟢	🟢	🟢	🟡
ubuntu-6.5	🟢	🟢	🟢	🟢	🟢	🟢

ARM64 kernel testing matrix

KERNEL	CMAKE-CONFIGURE	KMOD BUILD	KMOD SCAP-OPEN	BPF-PROBE BUILD	BPF-PROBE SCAP-OPEN	MODERN-BPF SCAP-OPEN
amazonlinux2-5.4	🟢	🟢	🟢	🟢	🟢	🟡
amazonlinux2022-5.15	🟢	🟢	🟢	🟢	🟢	🟢
fedora-6.2	🟢	🟢	🟢	🟢	🟢	🟢
oraclelinux-4.14	🟢	🟢	🟢	🟡	🟡	🟡
oraclelinux-5.15	🟢	🟢	🟢	🟢	🟢	🟢
ubuntu-6.5	🟢	🟢	🟢	🟢	🟢	🟢