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/machine.c b/tools/perf/util/machine.c
index fd192e4..51a6303 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1486,7 +1486,7 @@
 	    (!sample->user_stack.size))
 		return 0;
 
-	return unwind__get_entries(unwind_entry, &callchain_cursor, thread->mg->machine,
+	return unwind__get_entries(unwind_entry, &callchain_cursor,
 				   thread, sample, max_stack);
 
 }