Fix deadlock at the end of decoding.

For some h264 files, h264dec hangs at the end of decoding. This is
regression caused by the commit 1c23887. This patch fixes the
issue by adding SET_EVENT(&m_sReleaseBufferEvent) to SetOption(
DECODER_OPTION_END_OF_STREAM).

Author: tyan0

codec/decoder/plus/src/welsDecoderExt.cpp

@@ -513,6 +513,8 @@ long CWelsDecoder::SetOption (DECODER_OPTION eOptID, void* pOption) {
       if (pDecContext == NULL) return dsInitialOptExpected;
 
       pDecContext->bEndOfStreamFlag = iVal ? true : false;
+      if (iVal && m_iThreadCount >= 1)
+        SET_EVENT (&m_sReleaseBufferEvent);
 
       return cmResultSuccess;
     } else if (eOptID == DECODER_OPTION_ERROR_CON_IDC) { // Indicate error concealment status