winex11: Use RtlGetLastWin32Error() instead of GetLastError().

dlls/winex11.drv/clipboard.c

@@ -1655,7 +1655,7 @@ static UINT *get_clipboard_formats( UINT *size )
         if (!(ids = malloc( *size * sizeof(*ids) ))) return NULL;
         if (NtUserGetUpdatedClipboardFormats( ids, *size, size )) break;
         free( ids );
-        if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) return NULL;
+        if (RtlGetLastWin32Error() != ERROR_INSUFFICIENT_BUFFER) return NULL;
     }
     register_win32_formats( ids, *size );
     return ids;

dlls/winex11.drv/window.c

@@ -2067,7 +2067,7 @@ HWND create_foreign_window( Display *display, Window xwin )
         class.lpszClassName = classW;
         RtlInitUnicodeString( &class_name, classW );
         if (!NtUserRegisterClassExWOW( &class, &class_name, &version, NULL, 0, 0, NULL ) &&
-            GetLastError() != ERROR_CLASS_ALREADY_EXISTS)
+            RtlGetLastWin32Error() != ERROR_CLASS_ALREADY_EXISTS)
         {
             ERR( "Could not register foreign window class\n" );
             return FALSE;