Fix for crash in BLE receive thread.

Fix for crash in BLE receive thread.

Synchronizing access to client and server senderinfo as there are
chances of data receive handler may be acting on deleted SenderInfo
data when connection is closed. When connection closed, all senderInfo
for that connection are cleared in another thread.

https://github.sec.samsung.net/RS7-IOTIVITY/IoTivity/commit/69383ab5a059d7dd114c69d5d5ff5371b5946c98
(cherry picked from 69383ab5a059d7dd114c69d5d5ff5371b5946c98)

Change-Id: Ibc495dba0143eef908eaa35a0173dde77288d4be
Signed-off-by: Harish Kumara M <h.marappa@samsung.com>
Signed-off-by: DoHyun Pyun <dh79.pyun@samsung.com>