kbuild: uapi: rerun header tests when headers_check.pl changes

If the checks change they need to be rerun.

Add a Makefile dependency so this happens.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://lore.kernel.org/r/20250813-kbuild-hdrtest-fixes-v2-1-8a7921ca3a03@linutronix.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Author: t-8ch

usr/include/Makefile

@@ -85,7 +85,7 @@ quiet_cmd_hdrtest = HDRTEST $<
 		$(PERL) $(src)/headers_check.pl $(obj) $<; \
 		touch $@
 
-$(obj)/%.hdrtest: $(obj)/%.h FORCE
+$(obj)/%.hdrtest: $(obj)/%.h $(src)/headers_check.pl FORCE
 	$(call if_changed_dep,hdrtest)
 
 # Since GNU Make 4.3, $(patsubst $(obj)/%/,%,$(wildcard $(obj)/*/)) works.