mmsystem.dll16: Check for NULL ptr in mmioRename (Coverity).

dlls/mmsystem.dll16/mmio16.c

@@ -631,6 +631,7 @@ MMRESULT16 WINAPI mmioRename16(LPCSTR szFileName, LPCSTR szNewFileName,
         inst = TRUE;
     }
     memset(&mmioinfo, 0, sizeof(mmioinfo));
+    if (lpmmioinfo)
         mmioinfo.fccIOProc = lpmmioinfo->fccIOProc;
     ret = mmioRenameA(szFileName, szNewFileName, &mmioinfo, dwRenameFlags);
     if (inst) {