PVS-Studio warning V597 for Dolphin

void md5_hmac_starts( md5_context *ctx, unsigned char *key,
                      int keylen )
{
  ...
  memset( sum, 0, sizeof( sum ) );
}

This suspicious code was found in Dolphin project by PVS-Studio static code analyzer.
Warning message is:
V597 The compiler could delete the 'memset' function call, which is used to flush 'sum' buffer. The RtlSecureZeroMemory() function should be used to erase the private data. Common md5.cpp 353

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/