Ptrace: enable the process to read other process's stack and comm

Ptrace: enable the process to read other process's stack and comm

BZ: 36161

For debug usage,For debug ANR and UIWDT issues, we need get more details from the
/d/binder, /proc/xxx/stack, proc/xxx/comm, from it we can know which
process block the binder read, and we can also get more other useful
informations, but the current ptrace implement may block it. the patch
add a debugfs interface to enable read by default.
Signed-off-by: xiaobing tu <xiaobing.tu@intel.com>
Change-Id: Ied22eaa00316ff5e3602799af5825f2afb4fa21f
Reviewed-on: http://android.intel.com:8080/51907
Reviewed-by: Zhang, LongX <longx.zhang@intel.com>
Reviewed-by: Gross, Mark <mark.gross@intel.com>
Reviewed-by: Ren, Jack <jack.ren@intel.com>
Reviewed-by: Yang, Fei <fei.yang@intel.com>
Tested-by: Ng, Cheon-woei <cheon-woei.ng@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>