Remove (POINTER)NULL casts.

diff --git a/dlls/msacm/msacm32_main.c b/dlls/msacm/msacm32_main.c
index 6b7b39b..82317dc7 100644
--- a/dlls/msacm/msacm32_main.c
+++ b/dlls/msacm/msacm32_main.c
@@ -51,7 +51,7 @@
     case DLL_PROCESS_DETACH:
         MSACM_UnregisterAllDrivers();
         HeapDestroy(MSACM_hHeap);
-        MSACM_hHeap = (HANDLE)NULL;
+        MSACM_hHeap = NULL;
         MSACM_hInstance32 = NULL;
 	break;
     case DLL_THREAD_ATTACH: