tools build: Make the fixdep helper part of the build process

Making the fixdep helper to be invoked within dep-cmd.

Each user of the build framework needs to make sure fixdep exists before
executing the build itself.

If the build doesn't find fixdep, it falls back to the old style
dependency tracking.

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/1443004442-32660-6-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/build/Build.include

@@ -58,8 +58,14 @@ 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
+dep-cmd = $(if $(wildcard $(fixdep)),                                           \
+           $(fixdep) $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;           \
+           rm -f $(depfile);                                                    \
+           mv -f $(dot-target).tmp $(dot-target).cmd,                           \
+           printf '\# cannot find fixdep (%s)\n' $(fixdep) > $(dot-target).cmd; \
+           printf '\# using basic dep data\n\n' >> $(dot-target).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

tools/build/Makefile.build

@@ -21,6 +21,13 @@ endif
 
 build-dir := $(srctree)/tools/build
 
+# Define $(fixdep) for dep-cmd function
+ifeq ($(OUTPUT),)
+  fixdep := $(build-dir)/fixdep
+else
+  fixdep := $(OUTPUT)/fixdep
+endif
+
 # Generic definitions
 include $(build-dir)/Build.include