Fix crash on hangup: Runtime exception thrown rather than CallStateException

This is still an invalid state to reach to. However, all other invalid states
in this routine also throw CallStateException.

Bug: 17205457
Change-Id: Ib8c958a49f303f6babfeceeb900090a57116a17b
diff --git a/src/java/com/android/internal/telephony/imsphone/ImsPhoneCallTracker.java b/src/java/com/android/internal/telephony/imsphone/ImsPhoneCallTracker.java
index 0cbdd7c..eb10796 100644
--- a/src/java/com/android/internal/telephony/imsphone/ImsPhoneCallTracker.java
+++ b/src/java/com/android/internal/telephony/imsphone/ImsPhoneCallTracker.java
@@ -723,7 +723,7 @@
                 log("(backgnd) hangup waiting or background");
             }
         } else {
-            throw new RuntimeException ("ImsPhoneCall " + call +
+            throw new CallStateException ("ImsPhoneCall " + call +
                     "does not belong to ImsPhoneCallTracker " + this);
         }