Fix build

Still getting build errors from fc due to invalid partial template
specializations. Fix by hoisting the compiler flag to fix this from fc up
to eos as a whole.

CMakeLists.txt

@@ -126,6 +126,12 @@ else( WIN32 ) # Apple AND Linux
         if ( FULL_STATIC_BUILD )
           set( CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libstdc++ -static-libgcc")
         endif ( FULL_STATIC_BUILD )
+
+        if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
+            if( CMAKE_CXX_COMPILER_VERSION VERSION_EQUAL 4.0.0 OR CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 4.0.0 )
+                set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-invalid-partial-specialization" )
+            endif()
+        endif()
     endif( APPLE )
 
     if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" )