Bluetooth: Avoid fd leak for Bluetooth server socket connections

-As the close function of local socket implementation is dependent
 on mFdCreatedInternally, it will not be set for bluetooth server
 sockets, this will lead to fd leak on bluetooth socket connection.

-Exposed the API to set mFdCreatedExternally flag to close fd which
 was opened externally, so that when the actual close request comes
 fd will be closed successfully based on flag check.

CRs-Fixed: 638042
Change-Id: I22c6a973b30531407148f9d9e50820422d4427b0