DO NOT MERGE Fix potential DoS caused by delivering signal to BT process

Bug: 28885210
Change-Id: I63866d894bfca47464d6e42e3fb0357c4f94d360

 Conflicts:
	btif/co/bta_hh_co.c
	btif/src/btif_core.c
Merge conflict resolution of ag/1161415 (referencing ag/1164670)
- Directly into mnc-mr2-release

 static inline int btif_hl_select_close_connected(void){
     char sig_on = btif_hl_signal_select_close_connected;
     BTIF_TRACE_DEBUG("btif_hl_select_close_connected");
    return TEMP_FAILURE_RETRY(send(signal_fds[1], &sig_on, sizeof(sig_on), 0));
 }

 static inline int btif_hl_select_close_connected(void){
     char sig_on = btif_hl_signal_select_close_connected;
     BTIF_TRACE_DEBUG("btif_hl_select_close_connected");
    return send(signal_fds[1], &sig_on, sizeof(sig_on), 0);
 }
