Work in preparation for wiring up the remaining de-allocation and
abort bits.
1) limit to one attempt per call service upon multiple selectors
returning the same call service
2) record the failing/incompatible ones such that these are avoided
when switching
3) addressing some related todos etc.

Change-Id: I62204e9947bb8557888df33ca70f4352d3e6decf
diff --git a/src/com/android/telecomm/CallsManager.java b/src/com/android/telecomm/CallsManager.java
index 61f331b..cb9cab4 100644
--- a/src/com/android/telecomm/CallsManager.java
+++ b/src/com/android/telecomm/CallsManager.java
@@ -436,9 +436,9 @@
 
     /**
      * Stops playing the ringer if the specified call is the top-most incoming call. This exists
-     * separately from {@link #removeIncomingCall} for cases where we would like to stop playing the
-     * ringer for a call, but that call may still exist in {@link #mUnansweredIncomingCalls} - See
-     * {@link #rejectCall}, {@link #answerCall}.
+     * separately from {@link #removeFromUnansweredCalls} to allow stopping the ringer for calls
+     * that should remain in {@link #mUnansweredIncomingCalls}, invoked from {@link #answerCall}
+     * and {@link #rejectCall}.
      *
      * @param call The call for which we should stop ringing.
      */