Always pass -fcolor-diagnostics to clang.

Otherwise everyone using ninja to build is lacking colors.

cmake/modules/CheckCompiler.cmake

@@ -33,10 +33,12 @@ if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
   string(REGEX REPLACE "^.*[ ]version[ ][0-9]+\\.([0-9]+).*" "\\1" CLANG_MINOR "${_clang_version_info}")
   message(STATUS "Found Clang. Major version ${CLANG_MAJOR}, minor version ${CLANG_MINOR}")
   set(COMPILER_VERSION clang${CLANG_MAJOR}${CLANG_MINOR})
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fcolor-diagnostics")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fcolor-diagnostics")
   if(ccache)
     # https://bugzilla.samba.org/show_bug.cgi?id=8118 and color.
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Qunused-arguments -fcolor-diagnostics")
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Qunused-arguments -fcolor-diagnostics")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Qunused-arguments")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Qunused-arguments")
   endif()
 else()
   set(CLANG_MAJOR 0)