unix: enable building tix on macOS

It now builds properly. We still need to teach the Python build system
about it though.

Author: indygreg

cpython-unix/Makefile

@@ -33,7 +33,7 @@ ifeq ($(PLATFORM),macos)
     NEED_GDBM :=
     NEED_X11 :=
     NEED_READLINE :=
-    NEED_TIX :=
+    NEED_TIX := 1
 endif
 
 BASE_PLATFORM := $(PLATFORM)