selftests/nolibc: split out CFLAGS logic

Some upcoming changes will reuse the CFLAGS.

Split the computation into a reusable Makefile.

Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20250620-nolibc-selftests-v1-2-f6b2ce7c5071@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Author: t-8ch

tools/testing/selftests/nolibc/Makefile

@@ -195,14 +195,10 @@ CFLAGS_sparc32 = $(call cc-option,-m32)
 ifeq ($(origin XARCH),command line)
 CFLAGS_XARCH = $(CFLAGS_$(XARCH))
 endif
-_CFLAGS_STACKPROTECTOR = $(call cc-option,-fstack-protector-all) $(call cc-option,-mstack-protector-guard=global)
-CFLAGS_STACKPROTECTOR ?= $(call try-run, \
-	echo 'void foo(void) {}' | $(CC) -x c - -o - -S $(CLANG_CROSS_FLAGS) $(_CFLAGS_STACKPROTECTOR) | grep -q __stack_chk_guard, \
-	$(_CFLAGS_STACKPROTECTOR))
-CFLAGS_SANITIZER ?= $(call cc-option,-fsanitize=undefined -fsanitize-trap=all)
-CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 -W -Wall -Wextra \
-		$(call cc-option,-fno-stack-protector) $(call cc-option,-Wmissing-prototypes) \
-		$(CFLAGS_XARCH) $(CFLAGS_STACKPROTECTOR) $(CFLAGS_SANITIZER) $(CFLAGS_EXTRA)
+
+include Makefile.include
+
+CFLAGS  ?= $(CFLAGS_NOLIBC_TEST) $(CFLAGS_XARCH) $(CFLAGS_EXTRA)
 LDFLAGS :=
 
 LIBGCC := -lgcc

tools/testing/selftests/nolibc/Makefile.include

@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0
+
+__CFLAGS_STACKPROTECTOR = $(call cc-option,-fstack-protector-all) $(call cc-option,-mstack-protector-guard=global)
+_CFLAGS_STACKPROTECTOR ?= $(call try-run, \
+	echo 'void foo(void) {}' | $(CC) -x c - -o - -S $(CLANG_CROSS_FLAGS) $(__CFLAGS_STACKPROTECTOR) | grep -q __stack_chk_guard, \
+	$(__CFLAGS_STACKPROTECTOR))
+_CFLAGS_SANITIZER ?= $(call cc-option,-fsanitize=undefined -fsanitize-trap=all)
+CFLAGS_NOLIBC_TEST  ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 -W -Wall -Wextra \
+		$(call cc-option,-fno-stack-protector) $(call cc-option,-Wmissing-prototypes) \
+		$(_CFLAGS_STACKPROTECTOR) $(_CFLAGS_SANITIZER)