m4v_h263: fix global buffer overflow

Bug: 65025028
Test: run POC
Change-Id: Ifa5cf0e3ced7188ed70849b04b57828518ccb5bf
(cherry picked from commit 26a87d15ef97b35633577f7a97ed39bcaa800585)
diff --git a/media/libstagefright/codecs/m4v_h263/dec/src/vlc_decode.cpp b/media/libstagefright/codecs/m4v_h263/dec/src/vlc_decode.cpp
index f7192b1c..7202f98 100644
--- a/media/libstagefright/codecs/m4v_h263/dec/src/vlc_decode.cpp
+++ b/media/libstagefright/codecs/m4v_h263/dec/src/vlc_decode.cpp
@@ -560,7 +560,7 @@
 
     BitstreamShow13Bits(stream, &code);
 
-    if (code == 0)
+    if (code < 8)
     {
         return VLC_CODE_ERROR;
     }