Cleanup: avoid positional struct initialization

When moving to C++ field for initialization was removed.
Favor assignments to field names as it reads better and avoids bugs if
files are ever re-arranged as well as mistakes (see T94784).

Note that the generated optimized output is identical with GCC11.

source/blender/modifiers/intern/MOD_weld.cc

@@ -386,7 +386,10 @@ static Vector<WeldVert> weld_vert_ctx_alloc_and_setup(Span<int> vert_dest_map,
 
   for (const int i : vert_dest_map.index_range()) {
     if (vert_dest_map[i] != OUT_OF_CONTEXT) {
-      wvert.append({vert_dest_map[i], i});
+      WeldVert wv{};
+      wv.vert_dest = vert_dest_map[i];
+      wv.vert_orig = i;
+      wvert.append(wv);
     }
   }
   return wvert;