selftests/nolibc: use -nostdinc for nolibc-test

Avoid any accidental reliance on system includes.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

tools/testing/selftests/nolibc/Makefile

@@ -170,7 +170,7 @@ sysroot/$(ARCH)/include:
 ifneq ($(NOLIBC_SYSROOT),0)
 nolibc-test: nolibc-test.c sysroot/$(ARCH)/include
 	$(QUIET_CC)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ \
-	  -nostdlib -static -Isysroot/$(ARCH)/include $< -lgcc
+	  -nostdlib -nostdinc -static -Isysroot/$(ARCH)/include $< -lgcc
 else
 nolibc-test: nolibc-test.c
 	$(QUIET_CC)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ \