Enable IPC support on Cygwin.

The support was previously disabled due to compilation errors in
Boost.Interprocess, which were resolved.

Refs boostorg/interprocess#76.

CMakeLists.txt

@@ -306,8 +306,6 @@ else()
 endif()
 
 if (CYGWIN)
-    # Boost.Interprocess does not compile on Cygwin: https://github.com/boostorg/interprocess/issues/76
-    set(BOOST_LOG_WITHOUT_IPC ON)
     list(APPEND boost_log_common_private_defines
         __USE_W32_SOCKETS
         _XOPEN_SOURCE=600

build/Jamfile.v2

@@ -113,8 +113,6 @@ project boost/log
         <target-os>windows:<library>advapi32
 
         <target-os>cygwin:<define>BOOST_USE_WINDOWS_H
-        # Boost.Interprocess does not compile on Cygwin: https://github.com/boostorg/interprocess/issues/76
-        <target-os>cygwin:<define>BOOST_LOG_WITHOUT_IPC
         <target-os>cygwin:<library>ws2_32
         <target-os>cygwin:<library>mswsock
         <target-os>cygwin:<library>advapi32

doc/changelog.qbk

@@ -13,6 +13,7 @@
 
 * Disabled usage of `std::codecvt<char16_t>` and `std::codecvt<char32_t>` locale facets in C++20 and later modes as they were deprecated in C++20. This means character code conversions to/from `char16_t` and `char32_t` is no longer available in C++20 and later.
 * Fixed building issues when using CMake and MinGW-w64. ([pull_request 241])
+* Enabled support for inter-process communication (IPC) utilities on Cygwin. The support was previously disabled due to compilation issues in Boost.Interprocess, which were resolved.
 
 [heading 2.30, Boost 1.87]