[PATCH v2 2/2] kbuild: lto: preserve MAKEFLAGS for module linking

[Jiri Slaby <jslaby@suse.cz>]

From: Martin Liska <mliska@suse.cz>

Prefix command in makefile run in order to preserve access to jobserver.
This is needed for gcc at least.

Fixes this warning:
lto-wrapper: warning: jobserver is not available: ‘--jobserver-auth=’ is not present in ‘MAKEFLAGS’

Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Fixes: 5d45950dfbb1 (kbuild: move vmlinux.o link to scripts/Makefile.vmlinux_o)
Signed-off-by: Martin Liska <mliska@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

Notes:
    [v2] this is new in v2

 scripts/Makefile.build | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index bb63374fb055..493f3c4e8461 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -247,8 +247,8 @@ endef
 
 # Built-in and composite module parts
 $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
-	$(call if_changed_rule,cc_o_c)
-	$(call cmd,force_checksrc)
+	+$(call if_changed_rule,cc_o_c)
+	+$(call cmd,force_checksrc)
 
 # To make this rule robust against "Argument list too long" error,
 # ensure to add $(obj)/ prefix by a shell command.
@@ -457,7 +457,7 @@ endef
 $(multi-obj-m): objtool-enabled := $(delay-objtool)
 $(multi-obj-m): part-of-module := y
 $(multi-obj-m): %.o: %.mod FORCE
-	$(call if_changed_rule,ld_multi_m)
+	+$(call if_changed_rule,ld_multi_m)
 $(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
 
 targets := $(filter-out $(PHONY), $(targets))
-- 
2.37.1