mshtml: Fix compiler warnings with flag -Wcast-qual.

dlls/mshtml/dispex.c

@@ -248,12 +248,12 @@ static void add_func_info(dispex_data_t *data, DWORD *size, tid_t tid, const FUN
 
 static int dispid_cmp(const void *p1, const void *p2)
 {
-    return ((func_info_t*)p1)->id - ((func_info_t*)p2)->id;
+    return ((const func_info_t*)p1)->id - ((const func_info_t*)p2)->id;
 }
 
 static int func_name_cmp(const void *p1, const void *p2)
 {
-    return strcmpiW((*(func_info_t**)p1)->name, (*(func_info_t**)p2)->name);
+    return strcmpiW((*(func_info_t* const*)p1)->name, (*(func_info_t* const*)p2)->name);
 }
 
 static dispex_data_t *preprocess_dispex_data(DispatchEx *This)
@@ -322,7 +322,7 @@ static dispex_data_t *preprocess_dispex_data(DispatchEx *This)
 
 static int id_cmp(const void *p1, const void *p2)
 {
-    return *(DISPID*)p1 - *(DISPID*)p2;
+    return *(const DISPID*)p1 - *(const DISPID*)p2;
 }
 
 HRESULT get_dispids(tid_t tid, DWORD *ret_size, DISPID **ret)