shell32: Skip buffer allocation when querying drop file numbers.

dlls/shell32/shellole.c

@@ -578,7 +578,7 @@ UINT WINAPI DragQueryFileA(
         if(lpDropFileStruct->fWide) {
             LPWSTR lpszFileW = NULL;
 
-            if(lpszFile) {
+            if(lpszFile && lFile != 0xFFFFFFFF) {
                 lpszFileW = HeapAlloc(GetProcessHeap(), 0, lLength*sizeof(WCHAR));
                 if(lpszFileW == NULL) {
                     goto end;
@@ -633,7 +633,7 @@ UINT WINAPI DragQueryFileW(
         if(lpDropFileStruct->fWide == FALSE) {
             LPSTR lpszFileA = NULL;
 
-            if(lpszwFile) {
+            if(lpszwFile && lFile != 0xFFFFFFFF) {
                 lpszFileA = HeapAlloc(GetProcessHeap(), 0, lLength);
                 if(lpszFileA == NULL) {
                     goto end;

dlls/shell32/tests/shellole.c

@@ -760,7 +760,7 @@ static LRESULT WINAPI drop_window_proc(HWND hwnd, UINT msg, WPARAM wparam, LPARA
         num = DragQueryFileA(hDrop, 0xffffffff, NULL, 0);
         ok(num == 1, "expected 1, got %u\n", num);
         num = DragQueryFileA(hDrop, 0xffffffff, (char*)0xdeadbeef, 0xffffffff);
-        todo_wine ok(num == 1, "expected 1, got %u\n", num);
+        ok(num == 1, "expected 1, got %u\n", num);
         num = DragQueryFileA(hDrop, 0, filename, sizeof(filename));
         ok(num == strlen(DROPTEST_FILENAME), "got %u\n", num);
         ok(!strcmp(filename, DROPTEST_FILENAME), "got %s\n", filename);