[cmake]: Second try at making swift-api-digester work correctly.

Note: I ran into an issue compiling on Linux with STL 4.8 headers where
STL vector needs an iterator instead of a ``const_iterator``. Hopefully this will
not show on the CI machines.

http://stackoverflow.com/questions/19559235/missing-const-iterator-overload-of-stdvectorerase-with-g-4-8

Author: Doug Coleman

test/CMakeLists.txt

@@ -41,7 +41,8 @@ function(get_test_dependencies SDK result_var_name)
 
   set(deps_binaries
       swift swift-ide-test sil-opt swift-llvm-opt swift-demangle sil-extract
-      lldb-moduleimport-test swift-reflection-dump swift-remoteast-test)
+      lldb-moduleimport-test swift-reflection-dump swift-remoteast-test
+      swift-api-digester)
   if(NOT SWIFT_BUILT_STANDALONE)
     list(APPEND deps_binaries FileCheck arcmt-test c-arcmt-test c-index-test
          clang llc llvm-cov llvm-dwarfdump llvm-link llvm-profdata not)

tools/CMakeLists.txt

@@ -6,17 +6,12 @@ add_swift_tool_subdirectory(swift-demangle)
 add_swift_tool_subdirectory(lldb-moduleimport-test)
 add_swift_tool_subdirectory(sil-extract)
 add_swift_tool_subdirectory(swift-llvm-opt)
-
-if(SWIFT_HOST_VARIANT STREQUAL "macosx")
-  # Only build Darwin-specific tools when deploying to OS X.
-  add_swift_tool_subdirectory(swift-api-digester)
-endif()
+add_swift_tool_subdirectory(swift-api-digester)
 
 if(SWIFT_BUILD_SOURCEKIT)
   add_swift_tool_subdirectory(SourceKit)
 endif()
 
-
 is_sdk_requested("${SWIFT_HOST_VARIANT_SDK}" SWIFT_HOST_SDK_REQUESTED)
 if(SWIFT_BUILD_STDLIB AND SWIFT_HOST_SDK_REQUESTED)
   add_swift_tool_subdirectory(swift-reflection-dump)

tools/swift-api-digester/CMakeLists.txt

@@ -1,5 +1,5 @@
-add_swift_executable(swift-api-digester
+add_swift_host_tool(swift-api-digester
   swift-api-digester.cpp
-  LINK_LIBRARIES
-    swiftFrontend swiftIDE
+  LINK_LIBRARIES swiftFrontend swiftIDE
+  SWIFT_COMPONENT tools
 )