Better handling of codec initialization failure in the player and thumbnail extractor. Return a runtime error instead of asserting if the software MPEG4/H.263 decoder fails to initialize.

Change-Id: I5cba02ee85a41e43c2623053de40f26e2cf2efe4
related-to-bug: 2699505
diff --git a/media/libstagefright/StagefrightMetadataRetriever.cpp b/media/libstagefright/StagefrightMetadataRetriever.cpp
index 2968917..258be74 100644
--- a/media/libstagefright/StagefrightMetadataRetriever.cpp
+++ b/media/libstagefright/StagefrightMetadataRetriever.cpp
@@ -120,7 +120,11 @@
         return NULL;
     }
 
-    decoder->start();
+    status_t err = decoder->start();
+    if (err != OK) {
+        LOGW("OMXCodec::start returned error %d (0x%08x)\n", err, err);
+        return NULL;
+    }
 
     // Read one output buffer, ignore format change notifications
     // and spurious empty buffers.
@@ -134,7 +138,6 @@
     }
 
     MediaBuffer *buffer = NULL;
-    status_t err;
     do {
         if (buffer != NULL) {
             buffer->release();