CMake: Make ld.gold linker optional

Some platforms are having hard time using this linker so added an option
to not use it. The options is an advanced one and enabled by default so
should not cause any changes for current users.

CMakeLists.txt

@@ -508,6 +508,12 @@ mark_as_advanced(WITH_C11)
 option(WITH_CXX11 "Build with C++11 standard enabled, for development use only!" ${_cxx11_init})
 mark_as_advanced(WITH_CXX11)
 
+# Compiler toolchain
+if(CMAKE_COMPILER_IS_GNUCC)
+	option(WITH_LINKER_GOLD "Use ld.gold linker which is usually faster than ld.bfd" ON)
+	mark_as_advanced(WITH_LINKER_GOLD)
+endif()
+
 # Dependency graph
 option(WITH_LEGACY_DEPSGRAPH "Build Blender with legacy dependency graph" ON)
 mark_as_advanced(WITH_LEGACY_DEPSGRAPH)

build_files/cmake/platform/platform_unix.cmake

@@ -384,7 +384,7 @@ add_definitions(-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE
 if(CMAKE_COMPILER_IS_GNUCC)
 	set(PLATFORM_CFLAGS "-pipe -fPIC -funsigned-char -fno-strict-aliasing")
 
-	# use ld.gold linker if available, could make optional
+	if(WITH_LINKER_GOLD)
 		execute_process(
 			COMMAND ${CMAKE_C_COMPILER} -fuse-ld=gold -Wl,--version
 			ERROR_QUIET OUTPUT_VARIABLE LD_VERSION)
@@ -395,6 +395,7 @@ if(CMAKE_COMPILER_IS_GNUCC)
 			message(STATUS "GNU gold linker isn't available, using the default system linker.")
 		endif()
 		unset(LD_VERSION)
+	endif()
 
 # CLang is the same as GCC for now.
 elseif(CMAKE_C_COMPILER_ID MATCHES "Clang")