[CALL] Mark incoming call as waiting if there's an pending holding call.

Change-Id: I7d060d07a7e912d81af247511711aef965bc7470
[CALL] Fixed HANGUP_WAITING_OR_BACKGROUND

Change-Id: I6b1318a8e8b1bc3ecdfdc916afa2e906f257556f
[CALL] Small fix in ril_request_switch_waiting_or_holding_and_active

Change-Id: Ib822c0c91574d2ec93cf72bfb3c59876372f7b70