perf tools: Find the proc info under machine->root_dir.
perf tools: Find the proc info under machine->root_dir.

When we synthesize the threads, we are looking for the infomation under
/proc. But it is only for host.

This patch look for the path of proc under machine->root_dir, then
XXX__synthesize_threads() functions can support guest machines.

Signed-off-by: Dongsheng Yang <1b957dfff8d0f16ed124fab3c79d8c1232c34692@cn.fujitsu.com>
Cc: David Ahern <b80c1600f604d3b0d768f26f90a76757e76005dd@gmail.com>
Cc: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@kernel.org>
Cc: Jiri Olsa <2c6594f608aa3d41e98d48846a6328831f7084ad@redhat.com>
Cc: Namhyung Kim <1b20bcb62cf1b100c528e605608922000dc2fc80@lge.com>
Link: http://lkml.kernel.org/r/927b937da9177a079abafe4532fa9c9b60b5c4b7.1387572416.git.1b957dfff8d0f16ed124fab3c79d8c1232c34692@cn.fujitsu.com
Signed-off-by: Arnaldo Carvalho de Melo <293abb6b76d7791c0732cc517d38c4b5c734b87f@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs