perf machine: Introduce find_thread method

There are cases where we want just to find a thread if it exists
already, so provide a method for that.

While doing that start moving 'machine' methods to a separate file.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
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-8wpzqs9kfupng6xq8hx6lnxa@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index f9126f8..d80a333 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -300,6 +300,7 @@
 LIB_H += util/exec_cmd.h
 LIB_H += util/types.h
 LIB_H += util/levenshtein.h
+LIB_H += util/machine.h
 LIB_H += util/map.h
 LIB_H += util/parse-options.h
 LIB_H += util/parse-events.h
@@ -383,6 +384,7 @@
 LIB_OBJS += $(OUTPUT)util/callchain.o
 LIB_OBJS += $(OUTPUT)util/values.o
 LIB_OBJS += $(OUTPUT)util/debug.o
+LIB_OBJS += $(OUTPUT)util/machine.o
 LIB_OBJS += $(OUTPUT)util/map.o
 LIB_OBJS += $(OUTPUT)util/pstack.o
 LIB_OBJS += $(OUTPUT)util/session.o