Only enable colorized messages if g++ version is >=4.9

CMakeLists.txt

@@ -2,7 +2,18 @@ project( calamares )
 cmake_minimum_required( VERSION 2.8.12 )
 set( CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/CMakeModules" )
 #set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wl,--no-undefined" )
-set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -fdiagnostics-color=always" )
+set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11" )
+
+if( CMAKE_COMPILER_IS_GNUCXX )
+    execute_process( COMMAND ${CMAKE_C_COMPILER} -dumpversion
+                     OUTPUT_VARIABLE GCC_VERSION )
+    string( REGEX REPLACE "(\r?\n)+$" "" GCC_VERSION "${GCC_VERSION}" )
+    if( GCC_VERSION VERSION_GREATER 4.9 OR GCC_VERSION VERSION_EQUAL 4.9 )
+        message( STATUS "Found GNU g++ ${GCC_VERSION}, enabling colorized error messages." )
+        set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fdiagnostics-color=always" )
+    endif()
+endif()
+
 
 cmake_policy( SET CMP0023 OLD )