tools lib traceevent: Make dependency files regeneratable

Ingo reported that libtraceevent doesn't clean out dependency (.d) files
and it can cause a build error when the libgcc package upgraded:

comet:~/tip/tools/perf> make -j
SUBDIR ../lib/traceevent/
make[1]: *** No rule to make target `/usr/lib/gcc/x86_64-redhat-linux/4.7.0/include/stddef.h',
needed by `event-parse.o'. Stop.
make: *** [../lib/traceevent//libtraceevent.a] Error 2

So this patch makes the .d files depends on the source and header files
also, so that it can be re-generated as needed.

NOTE: This code is copied from the GNU make manual page
(4.14 Generating Prerequisites Automatically).

Reported-by: Ingo Molnar <[e-mail]>
Signed-off-by: Namhyung Kim <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/traceevent/Makefile

···
 all_objs := $(sort $(ALL_OBJS))
 all_deps := $(all_objs:%.o=.%.d)
 
+# let .d file also depends on the source and header files
 define check_deps
-		$(CC) -M $(CFLAGS) $< > $@;
+		@set -e; $(RM) $@; \
+		$(CC) -M $(CFLAGS) $< > $@.$$$$; \
+		sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \
+		$(RM) $@.$$$$
 endef
 
 $(gui_deps): ks_version.h