perf callchains: Use thread->mg->machine

The unwind__get_entries() already receives the thread parameter, from where it can
obtain the matching machine structure, shorten the signature.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jean Pihet <jean.pihet@linaro.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
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-isjc6bm8mv4612mhi6af64go@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
index f24b350..2dcfe9a 100644
--- a/tools/perf/util/unwind-libdw.c
+++ b/tools/perf/util/unwind-libdw.c
@@ -164,14 +164,14 @@
 }
 
 int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
-			struct machine *machine, struct thread *thread,
+			struct thread *thread,
 			struct perf_sample *data,
 			int max_stack)
 {
 	struct unwind_info ui = {
 		.sample		= data,
 		.thread		= thread,
-		.machine	= machine,
+		.machine	= thread->mg->machine,
 		.cb		= cb,
 		.arg		= arg,
 		.max_stack	= max_stack,