[PATCH] x86/build: correctly record dependencies of asm-offsets.s

[Jan Beulich <jbeulich@xxxxxxxx>]

Going through an intermediate *.new file requires telling the compiler
what the real target is, so that the inclusion of the resulting .*.d
file will actually be useful.

Fixes: 7d2d7a43d014 ("x86/build: limit rebuilding of asm-offsets.h")
Reported-by: Julien Grall <julien@xxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Already on the original patch I did suggest that perhaps Arm would want
to follow suit. So again - perhaps the rules should be unified by moving
to common code?

--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -241,7 +241,7 @@ efi/buildid.o efi/relocs-dummy.o: $(BASE
 efi/buildid.o efi/relocs-dummy.o: ;
 
 asm-offsets.s: $(TARGET_SUBARCH)/asm-offsets.c 
$(BASEDIR)/include/asm-x86/asm-macros.h
-       $(CC) $(filter-out -Wa$(comma)% -flto,$(c_flags)) -S -g0 -o $@.new $<
+       $(CC) $(filter-out -Wa$(comma)% -flto,$(c_flags)) -S -g0 -o $@.new -MQ 
$@ $<
        $(call move-if-changed,$@.new,$@)
 
 asm-macros.i: CFLAGS-y += -D__ASSEMBLY__ -P