perf build: Add arch powerpc objects building

Move the powerpc arch objects building under build framework to be
included in the libperf build object.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-nqrtlipvjptdyjfuzlnegqgu@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/powerpc/Build

+libperf-y += util/

tools/perf/arch/powerpc/Makefile

 ifndef NO_DWARF
 PERF_HAVE_DWARF_REGS := 1
-LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o
-LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/skip-callchain-idx.o
 endif
-LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/header.o

tools/perf/arch/powerpc/util/Build

+libperf-y += header.o
+
+libperf-$(CONFIG_DWARF) += dwarf-regs.o
+libperf-$(CONFIG_DWARF) += skip-callchain-idx.o