kbuild: add real-prereqs shorthand for $(filter-out FORCE, $^)

Backport from kernel
commit afa974b77128 ("kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^)")

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 10f31a5..73e1d71 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -356,7 +356,7 @@
 #
 ifdef lib-target
 quiet_cmd_link_l_target = AR      $@
-cmd_link_l_target = rm -f $@; $(AR) cDPrsT$(KBUILD_ARFLAGS) $@ $(lib-y)
+cmd_link_l_target = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
 
 $(lib-target): $(lib-y) FORCE
 	$(call if_changed,link_l_target)