selftests/nolibc: enable compiler warnings

It will help the developers to avoid cruft and detect some bugs.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

tools/testing/selftests/nolibc/Makefile

@@ -79,7 +79,7 @@ endif
 CFLAGS_s390 = -m64
 CFLAGS_mips = -EL
 CFLAGS_STACKPROTECTOR ?= $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all))
-CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 \
+CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 -W -Wall -Wextra \
 		$(call cc-option,-fno-stack-protector) \
 		$(CFLAGS_$(ARCH)) $(CFLAGS_STACKPROTECTOR)
 LDFLAGS :=