winmm: Cast-qual warnings fix (2 of 2)

[Andrew Talbot]

Changelog:
    winmm: Cast-qual warnings fix.

diff -urN a/dlls/winmm/playsound.c b/dlls/winmm/playsound.c
--- a/dlls/winmm/playsound.c	2006-11-09 17:45:35.000000000 +0000
+++ b/dlls/winmm/playsound.c	2006-11-22 16:07:42.000000000 +0000
@@ -220,10 +220,10 @@
         {
             if (fdwSound & SND_ASYNC)
             {
-                wps->pszSound = HeapAlloc(GetProcessHeap(), 0,
-                                          (lstrlenW(pszSound)+1) * sizeof(WCHAR));
-                if (!wps->pszSound) goto oom_error;
-                lstrcpyW((LPWSTR)wps->pszSound, pszSound);
+                LPWSTR sound = HeapAlloc(GetProcessHeap(), 0,
+                                         (lstrlenW(pszSound)+1) * sizeof(WCHAR));
+                if (!sound) goto oom_error;
+                wps->pszSound = lstrcpyW(sound, pszSound);
                 wps->bAlloc = TRUE;
             }
             else