tools build: Move dependency copy into function

So it's easier to add more functionality in the following commit.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1443004442-32660-5-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/build/Build.include

@@ -54,15 +54,20 @@ make-cmd = $(call escsq,$(subst \#,\\\#,$(subst $$,$$$$,$(cmd_$(1)))))
 # PHONY targets skipped in both cases.
 any-prereq = $(filter-out $(PHONY),$?) $(filter-out $(PHONY) $(wildcard $^),$^)
 
+###
+# Copy dependency data into .cmd file
+#  - gcc -M dependency info
+#  - command line to create object 'cmd_object :='
+dep-cmd = cat $(depfile) >  $(dot-target).cmd; \
+          printf '%s\n' 'cmd_$@ := $(make-cmd)' >> $(dot-target).cmd
+
 ###
 # if_changed_dep  - execute command if any prerequisite is newer than
 #                   target, or command line has changed and update
 #                   dependencies in the cmd file
 if_changed_dep = $(if $(strip $(any-prereq) $(arg-check)),         \
 	@set -e;                                                   \
-	$(echo-cmd) $(cmd_$(1));                                   \
+	$(echo-cmd) $(cmd_$(1)) && $(dep-cmd))
-	cat $(depfile) > $(dot-target).cmd;                        \
-	printf '%s\n' 'cmd_$@ := $(make-cmd)' >> $(dot-target).cmd)
 
 # if_changed      - execute command if any prerequisite is newer than
 #                   target, or command line has changed