winmm: Save data that was not yet written in mmioSetInfo.

dlls/winmm/mmio.c

@@ -965,9 +965,7 @@ MMRESULT WINAPI mmioSetInfo(HMMIO hmmio, const MMIOINFO* lpmmioinfo, UINT uFlags
             lpmmioinfo->pchEndWrite > wm->info.pchBuffer + wm->info.cchBuffer)
         return MMSYSERR_INVALPARAM;
 
-    wm->info.pchNext = lpmmioinfo->pchNext;
-    wm->info.pchEndRead = lpmmioinfo->pchEndRead;
-
+    wm->info = *lpmmioinfo;
     return MMSYSERR_NOERROR;
 }