Disable gcc warning about suggested parenthesis

Deuce doesn't want to add "useless parenthesis" to xbr.c.
Hopefully Clang will just ignore this -Wno-* option?
warning: suggest parentheses around ‘&&’ within ‘||’

src/conio/GNUmakefile

@@ -4,6 +4,9 @@ include $(SRC_ROOT)/build/Common.gmake	# defines clean and output directory rule
 
 CFLAGS += $(XPDEV-MT_CFLAGS) $(HASH_CFLAGS) $(ENCODE_CFLAGS) $(CIOLIB-MT_CFLAGS)
 
+# Deuce doesn't want to add "useless parens" in xbr.c
+CFLAGS += -Wno-parentheses
+
 ifeq ($(os),win32)
  OBJS	+=	$(MTOBJODIR)$(DIRSEP)SDL_win32_main$(OFILE)
  OBJS	+=	$(MTOBJODIR)$(DIRSEP)win32cio$(OFILE)