COMP: Remove gold linker support

Deprecated and does conflicts with LTO. Closes #1952

CMake/ITKSetStandardCompilerFlags.cmake

@@ -328,29 +328,6 @@ macro(check_compiler_platform_flags)
       set(ITK_REQUIRED_CXX_FLAGS "${ITK_REQUIRED_CXX_FLAGS} -Wno-array-bounds")
     endif()
 
-    if("${CMAKE_SYSTEM_NAME}" MATCHES "Linux")
-      set(_safe_cmake_required_flags "${CMAKE_REQUIRED_FLAGS}")
-      set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -fuse-ld=gold")
-      CHECK_CXX_SOURCE_COMPILES("int main() { return 0;}" have_gold)
-      set(CMAKE_REQUIRED_FLAGS "${_safe_cmake_required_flags}")
-      if(have_gold)
-        set(_use_gold_linker_default ON)
-        set(_gold_linker_failure_condition_0 "${CMAKE_CXX_COMPILER_VERSION}" VERSION_LESS "4.9.0")
-        set(_gold_linker_failure_condition_1  NOT BUILD_SHARED_LIBS AND "${CMAKE_CXX_COMPILER_VERSION}" VERSION_EQUAL "4.9.0")
-        if( (${_gold_linker_failure_condition_0}) OR (${_gold_linker_failure_condition_1}) )
-          set(_use_gold_linker_default OFF)
-        endif()
-        option(ITK_USE_GOLD_LINKER "Use the gold linker instead of ld." ${_use_gold_linker_default})
-        mark_as_advanced(ITK_USE_GOLD_LINKER)
-        # The gold linker is approximately 3X faster.
-        if(ITK_USE_GOLD_LINKER)
-          set(CMAKE_EXE_LINKER_FLAGS "-fuse-ld=gold ${CMAKE_EXE_LINKER_FLAGS}")
-          set(CMAKE_MODULE_LINKER_FLAGS "-fuse-ld=gold ${CMAKE_MODULE_LINKER_FLAGS}")
-          set(CMAKE_SHARED_LINKER_FLAGS "-fuse-ld=gold ${CMAKE_SHARED_LINKER_FLAGS}")
-        endif()
-      endif()
-    endif()
-
     if(APPLE)
       option(ITK_USE_64BITS_APPLE_TRUNCATION_WARNING "Turn on warnings on 64bits to 32bits truncations." OFF)
       mark_as_advanced(ITK_USE_64BITS_APPLE_TRUNCATION_WARNING)