winemac: Use a designated initializer to silence a compiler warning.

dlls/winemac.drv/event.c

@@ -290,7 +290,7 @@ BOOL query_ime_char_rect(macdrv_query* query)
     void *himc = query->ime_char_rect.data;
     CFRange *range = &query->ime_char_rect.range;
     CGRect *rect = &query->ime_char_rect.rect;
-    struct ime_query_char_rect_result result = {0};
+    struct ime_query_char_rect_result result = { .location = 0 };
     struct ime_query_char_rect_params params;
     BOOL ret;