perf tools: Fix parallel build

Parallel builds of perf were failing for me on a 32p box, with:

    * new build flags or prefix
util/pmu.l:7:23: error: pmu-bison.h: No such file or directory

...

make: *** [util/pmu-flex.o] Error 1
make: *** Waiting for unfinished jobs....

This can pretty quickly be seen by adding a sleep in front of the bison
calls in tools/perf/Makefile and running make -j4 on a smaller box i.e.:

	sleep 10; $(QUIET_BISON)$(BISON) -v util/pmu.y -d -o $(OUTPUT)util/pmu-bison.c

Adding the following dependencies fixes it for me.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/505BD190.40707@redhat.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile

@@ -233,13 +233,13 @@ export PERL_PATH
 FLEX = flex
 BISON= bison
 
-$(OUTPUT)util/parse-events-flex.c: util/parse-events.l
+$(OUTPUT)util/parse-events-flex.c: util/parse-events.l $(OUTPUT)util/parse-events-bison.c
 	$(QUIET_FLEX)$(FLEX) --header-file=$(OUTPUT)util/parse-events-flex.h $(PARSER_DEBUG_FLEX) -t util/parse-events.l > $(OUTPUT)util/parse-events-flex.c
 
 $(OUTPUT)util/parse-events-bison.c: util/parse-events.y
 	$(QUIET_BISON)$(BISON) -v util/parse-events.y -d $(PARSER_DEBUG_BISON) -o $(OUTPUT)util/parse-events-bison.c
 
-$(OUTPUT)util/pmu-flex.c: util/pmu.l
+$(OUTPUT)util/pmu-flex.c: util/pmu.l $(OUTPUT)util/pmu-bison.c
 	$(QUIET_FLEX)$(FLEX) --header-file=$(OUTPUT)util/pmu-flex.h -t util/pmu.l > $(OUTPUT)util/pmu-flex.c
 
 $(OUTPUT)util/pmu-bison.c: util/pmu.y