cflags: add -fdiagnostics-color if supported

makefiles/cflags.inc.mk

@@ -25,6 +25,11 @@ ifeq ($(shell $(CC) -fno-delete-null-pointer-checks -E - 2>/dev/null >/dev/null
   endif
 endif
 
+# Use colored gcc output if the compiler supports this
+ifeq ($(shell $(CC) -fdiagnostics-color -E - 2>/dev/null >/dev/null </dev/null ; echo $$?),0)
+  CFLAGS += -fdiagnostics-color
+endif
+
 # Fast-out on old style function definitions.
 # They cause unreadable error compiler errors on missing semicolons.
 # Worse yet they hide errors by accepting wildcard argument types.