fix mms crash when large video file is sent

If we try to attach a video with size more than allowed by
CarrierContentRestriction in the Messaging  application
(ComposeMessageActivity), the app crashes since it tries to delete a
message from database with improper URI (null value). Prevent the
deletion of message with null URI in correctAttachmentSize()

Change-Id: Icc08419accc23f13e80376b2078b2494815ee87f

Signed-off-by: Madan Ankapura <mankapur@sta.samsung.com>

src/com/android/mms/data/WorkingMessage.java

@@ -234,8 +234,10 @@ private void correctAttachmentState() {
         if (slideCount == 0) {
             mAttachmentType = TEXT;
             mSlideshow = null;
-            asyncDelete(mMessageUri, null, null);
-            mMessageUri = null;
+            if (mMessageUri != null) {
+                asyncDelete(mMessageUri, null, null);
+                mMessageUri = null;
+            }
         } else if (slideCount > 1) {
             mAttachmentType = SLIDESHOW;
         } else {