[PATCH] ppc32: make -j12 all fails in uImage target

make -j zImage may call if_changed twice at the same time, the result is a
corrupted vmlinux.gz

Write to a temporary file for the time being until someone with make skills
fix the serialization properly.
Signed-off-by: Olaf Hering <olh@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Tom Rini <trini@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc/boot/images/Makefile

@@ -6,12 +6,17 @@ MKIMAGE		:= $(srctree)/scripts/mkuboot.sh
 
 extra-y		:= vmlinux.bin vmlinux.gz
 
+# two make processes may write to vmlinux.gz at the same time with make -j
+quiet_cmd_mygzip = GZIP    $@
+cmd_mygzip = gzip -f -9 < $< > $@.$$$$ && mv $@.$$$$ $@
+
+
 OBJCOPYFLAGS_vmlinux.bin := -O binary
 $(obj)/vmlinux.bin: vmlinux FORCE
 	$(call if_changed,objcopy)
 
 $(obj)/vmlinux.gz: $(obj)/vmlinux.bin FORCE
-	$(call if_changed,gzip)
+	$(call if_changed,mygzip)
 
 quiet_cmd_uimage = UIMAGE  $@
       cmd_uimage = $(CONFIG_SHELL) $(MKIMAGE) -A ppc -O linux -T kernel \