perf tools: Compile perf with libperf-in.o instead of libperf.a

There's no need for perf build to use libperf.a,
we can use directly libperf-in.o.

The libperf.a stays as a target if needed:

  $ make libperf.a
  ...
    CC       util/pmu.o
    CC       util/pmu-flex.o
    LD       util/libperf-in.o
    LD       libperf-in.o
    AR       libperf.a
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190213123246.4015-2-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Makefile.perf

@@ -346,7 +346,7 @@ export PERL_PATH
 
 LIB_FILE=$(OUTPUT)libperf.a
 
-PERFLIBS = $(LIB_FILE) $(LIBAPI) $(LIBTRACEEVENT) $(LIBSUBCMD)
+PERFLIBS = $(LIBAPI) $(LIBTRACEEVENT) $(LIBSUBCMD)
 ifndef NO_LIBBPF
   PERFLIBS += $(LIBBPF)
 endif
@@ -549,6 +549,8 @@ JEVENTS_IN    := $(OUTPUT)pmu-events/jevents-in.o
 
 PMU_EVENTS_IN := $(OUTPUT)pmu-events/pmu-events-in.o
 
+LIBPERF_IN := $(OUTPUT)libperf-in.o
+
 export JEVENTS
 
 build := -f $(srctree)/tools/build/Makefile.build dir=. obj
@@ -565,9 +567,12 @@ $(JEVENTS): $(JEVENTS_IN)
 $(PMU_EVENTS_IN): $(JEVENTS) FORCE
 	$(Q)$(MAKE) -f $(srctree)/tools/build/Makefile.build dir=pmu-events obj=pmu-events
 
-$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN) $(PMU_EVENTS_IN) $(LIBTRACEEVENT_DYNAMIC_LIST)
+$(LIBPERF_IN): prepare FORCE
+	$(Q)$(MAKE) $(build)=libperf
+
+$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN) $(PMU_EVENTS_IN) $(LIBPERF_IN) $(LIBTRACEEVENT_DYNAMIC_LIST)
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(LIBTRACEEVENT_DYNAMIC_LIST_LDFLAGS) \
-		$(PERF_IN) $(PMU_EVENTS_IN) $(LIBS) -o $@
+		$(PERF_IN) $(PMU_EVENTS_IN) $(LIBPERF_IN) $(LIBS) -o $@
 
 $(GTK_IN): FORCE
 	$(Q)$(MAKE) $(build)=gtk
@@ -683,11 +688,6 @@ endif
 
 $(patsubst perf-%,%.o,$(PROGRAMS)): $(wildcard */*.h)
 
-LIBPERF_IN := $(OUTPUT)libperf-in.o
-
-$(LIBPERF_IN): prepare FORCE
-	$(Q)$(MAKE) $(build)=libperf
-
 $(LIB_FILE): $(LIBPERF_IN)
 	$(QUIET_AR)$(RM) $@ && $(AR) rcs $@ $(LIBPERF_IN) $(LIB_OBJS)