Split link flags and link libraries lists to make gold happy.

gold is more strict than lld about the order of the arguments, that's
why CMake offers two different properties for the linker: LINK_FLAGS and
LINK_LIBRARIES. The former _add_variant_link_flags was adding the
libraries to LINK_FLAGS, when the correct thing is to add them to
LINK_LIBRARIES.

The change adds a new output variable for _add_variant_link_flags which
will containt the linked libraries, and CMake will be able to generate
the correct command line invocation for when gold is used.

This should fix the Android CI build.

Author: drodriguez

cmake/modules/AddSwift.cmake

@@ -376,7 +376,7 @@ endfunction()
 function(_add_variant_link_flags)
   set(oneValueArgs SDK ARCH BUILD_TYPE ENABLE_ASSERTIONS ANALYZE_CODE_COVERAGE
   DEPLOYMENT_VERSION_OSX DEPLOYMENT_VERSION_IOS DEPLOYMENT_VERSION_TVOS DEPLOYMENT_VERSION_WATCHOS
-  RESULT_VAR_NAME ENABLE_LTO LTO_OBJECT_NAME LIBRARY_SEARCH_DIRECTORIES_VAR_NAME)
+  RESULT_VAR_NAME ENABLE_LTO LTO_OBJECT_NAME LINK_LIBRARIES_VAR_NAME LIBRARY_SEARCH_DIRECTORIES_VAR_NAME)
   cmake_parse_arguments(LFLAGS
     ""
     "${oneValueArgs}"
@@ -387,6 +387,7 @@ function(_add_variant_link_flags)
   precondition(LFLAGS_ARCH MESSAGE "Should specify an architecture")
 
   set(result ${${LFLAGS_RESULT_VAR_NAME}})
+  set(link_libraries ${${LFLAGS_LINK_LIBRARIES_VAR_NAME}})
   set(library_search_directories ${${LFLAGS_LIBRARY_SEARCH_DIRECTORIES_VAR_NAME}})
 
   _add_variant_c_compile_link_flags(
@@ -403,9 +404,9 @@ function(_add_variant_link_flags)
     RESULT_VAR_NAME result)
 
   if("${LFLAGS_SDK}" STREQUAL "LINUX")
-    list(APPEND result "-lpthread" "-latomic" "-ldl")
+    list(APPEND link_libraries "pthread" "atomic" "dl")
   elseif("${LFLAGS_SDK}" STREQUAL "FREEBSD")
-    list(APPEND result "-lpthread")
+    list(APPEND link_libraries "pthread")
   elseif("${LFLAGS_SDK}" STREQUAL "CYGWIN")
     # No extra libraries required.
   elseif("${LFLAGS_SDK}" STREQUAL "WINDOWS")
@@ -423,9 +424,10 @@ function(_add_variant_link_flags)
     list(APPEND library_search_directories
          ${CMAKE_BINARY_DIR}/winsdk_lib_${LFLAGS_ARCH}_symlinks)
   elseif("${LFLAGS_SDK}" STREQUAL "HAIKU")
-    list(APPEND result "-lbsd" "-latomic" "-Wl,-Bsymbolic")
+    list(APPEND link_libraries "bsd" "atomic")
+    list(APPEND result "-Wl,-Bsymbolic")
   elseif("${LFLAGS_SDK}" STREQUAL "ANDROID")
-    list(APPEND result "-ldl" "-llog" "-latomic" "-licudataswift" "-licui18nswift" "-licuucswift")
+    list(APPEND link_libraries "dl" "log" "atomic" "icudataswift" "icui18nswift" "icuucswift")
     if("${LFLAGS_ARCH}" MATCHES armv7)
       list(APPEND result "${SWIFT_ANDROID_NDK_PATH}/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a/libc++_shared.so")
     elseif("${LFLAGS_ARCH}" MATCHES aarch64)
@@ -435,7 +437,7 @@ function(_add_variant_link_flags)
     endif()
     swift_android_lib_for_arch(${LFLAGS_ARCH} ${LFLAGS_ARCH}_LIB)
     foreach(path IN LISTS ${LFLAGS_ARCH}_LIB)
-      list(APPEND library_search_directories ${path}) 
+      list(APPEND library_search_directories ${path})
     endforeach()
   else()
     # If lto is enabled, we need to add the object path flag so that the LTO code
@@ -475,6 +477,7 @@ function(_add_variant_link_flags)
   endif()
 
   set("${LFLAGS_RESULT_VAR_NAME}" "${result}" PARENT_SCOPE)
+  set("${LFLAGS_LINK_LIBRARIES_VAR_NAME}" "${link_libraries}" PARENT_SCOPE)
   set("${LFLAGS_LIBRARY_SEARCH_DIRECTORIES_VAR_NAME}" "${library_search_directories}" PARENT_SCOPE)
 endfunction()
 
@@ -1207,6 +1210,7 @@ function(_add_swift_library_single target name)
     DEPLOYMENT_VERSION_TVOS "${SWIFTLIB_DEPLOYMENT_VERSION_TVOS}"
     DEPLOYMENT_VERSION_WATCHOS "${SWIFTLIB_DEPLOYMENT_VERSION_WATCHOS}"
     RESULT_VAR_NAME link_flags
+    LINK_LIBRARIES_VAR_NAME link_libraries
     LIBRARY_SEARCH_DIRECTORIES_VAR_NAME library_search_directories
       )
 
@@ -1251,6 +1255,7 @@ function(_add_swift_library_single target name)
       COMPILE_FLAGS " ${c_compile_flags}")
   set_property(TARGET "${target}" APPEND_STRING PROPERTY
       LINK_FLAGS " ${link_flags}")
+  set_property(TARGET "${target}" APPEND PROPERTY LINK_LIBRARIES ${link_libraries})
   swift_target_link_search_directories("${target}" "${library_search_directories}")
 
   # Adjust the linked libraries for windows targets.  On Windows, the link is
@@ -2119,6 +2124,7 @@ function(_add_swift_executable_single name)
     LTO_OBJECT_NAME "${name}-${SWIFTEXE_SINGLE_SDK}-${SWIFTEXE_SINGLE_ARCHITECTURE}"
     ANALYZE_CODE_COVERAGE "${SWIFT_ANALYZE_CODE_COVERAGE}"
     RESULT_VAR_NAME link_flags
+    LINK_LIBRARIES_VAR_NAME link_libraries
     LIBRARY_SEARCH_DIRECTORIES_VAR_NAME library_search_directories)
 
   if(${SWIFTEXE_SINGLE_SDK} IN_LIST SWIFT_APPLE_PLATFORMS)
@@ -2176,6 +2182,7 @@ function(_add_swift_executable_single name)
   swift_target_link_search_directories("${name}" "${library_search_directories}")
   set_property(TARGET ${name} APPEND_STRING PROPERTY
       LINK_FLAGS " ${link_flags}")
+  set_property(TARGET ${name} APPEND PROPERTY LINK_LIBRARIES ${link_libraries})
   if (SWIFT_PARALLEL_LINK_JOBS)
     set_property(TARGET ${name} PROPERTY JOB_POOL_LINK swift_link_job_pool)
   endif()