Add RIL_UNSOL_RESEND_INCALL_MUTE.

For bug 2400052.

Notification requires user resend mute/unmute to get uplink audio in a call.
diff --git a/libril/ril.cpp b/libril/ril.cpp
index 6f36b8d..8ec9bba 100644
--- a/libril/ril.cpp
+++ b/libril/ril.cpp
@@ -3025,6 +3025,7 @@
         case RIL_UNSOL_CDMA_INFO_REC: return "UNSOL_CDMA_INFO_REC";
         case RIL_UNSOL_OEM_HOOK_RAW: return "UNSOL_OEM_HOOK_RAW";
         case RIL_UNSOL_RINGBACK_TONE: return "UNSOL_RINGBACK_TONE";
+        case RIL_UNSOL_RESEND_INCALL_MUTE: return "UNSOL_RESEND_INCALL_MUTE";
         default: return "<unknown request>";
     }
 }