BUG: 2321 Should not check on Mac machines

The linker ld for OSX does not have --as-needed and --no-as-needed
flags.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21167 3bd1e089-480b-0410-8dfb-8563597acbee

CMakeLists.txt

@@ -82,7 +82,7 @@ endif()
 #-----------------------------------------------------------------------------
 # Check if the linker will resolve symbols of underlinked libraries
 #-----------------------------------------------------------------------------
-if(UNIX)
+if(UNIX AND NOT APPLE)
   include(SlicerLinkerAsNeededFlagCheck)
   if(Slicer_LINKER_NO_AS_NEEDED_FLAG_REQUIRED)
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,--no-as-needed"