makefiles/color.inc.mk: don't set CC_NOCOLOR

If CC_NOCOLOR was not set by the user it was set according to the
terminal support of colored output.

But since CC_NOCOLOR is also used to set `-fdiagnostics-color` flags
this means changing `CFLAGS` according to terminal support of colored
output.

This is not needed for `-fdiagnostics-color` since this option is by
default `auto` if the compiler supports colored output, and `auto`
means it will only use color when standard error is a terminal.

makefiles/color.inc.mk

@@ -7,25 +7,22 @@ COLOR_PURPLE :=
 COLOR_RESET  :=
 COLOR_ECHO   := /bin/echo
 
-ifeq ($(CC_NOCOLOR),)
+# Check if colored output is not disabled by user, i.e: CC_NOCOLOR unset
+# or 0
+ifneq ($(CC_NOCOLOR),1)
   IS_TERMINAL = $(if $(MAKE_TERMOUT),$(MAKE_TERMERR),)
-  ifeq ($(IS_TERMINAL),)
-    CC_NOCOLOR = 1
-  else
-    CC_NOCOLOR = 0
-  endif
-endif
-
-ifeq ($(CC_NOCOLOR),0)
-  COLOR_GREEN  := \033[1;32m
-  COLOR_RED    := \033[1;31m
-  COLOR_YELLOW := \033[1;33m
-  COLOR_PURPLE := \033[1;35m
-  COLOR_RESET  := \033[0m
-  ifeq ($(OS),Darwin)
-    COLOR_ECHO   := echo -e
-    SHELL=bash
-  else
-    COLOR_ECHO   := /bin/echo -e
+  # Check if terminal support colored output
+  ifneq ($(IS_TERMINAL),)
+    COLOR_GREEN  := \033[1;32m
+    COLOR_RED    := \033[1;31m
+    COLOR_YELLOW := \033[1;33m
+    COLOR_PURPLE := \033[1;35m
+    COLOR_RESET  := \033[0m
+    ifeq ($(OS),Darwin)
+      COLOR_ECHO   := echo -e
+      SHELL=bash
+    else
+      COLOR_ECHO   := /bin/echo -e
+    endif
   endif
 endif