[4/6] wsdapi: Implement "Hello" message creation support.

[Vincent Povirk]

-    obj = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*obj));
+    heap = GetProcessHeap();
+    obj = HeapAlloc(heap, HEAP_ZERO_MEMORY, sizeof(*obj));

I really hope we don't have to start optimizing for fewer GetProcessHeap calls.

+        /* Calculate space needed, including colon and potential
trailing space */
+        memoryNeeded = sizeof(WCHAR) *
(lstrlenW(cur->Element->LocalName) +
lstrlenW(cur->Element->Space->PreferredPrefix) + 2);

This doesn't account for the terminating NULL wsprintfW will add.

+    discoveredNamespaces = WSDAllocateLinkedMemory(NULL, sizeof(struct list));
+    if (!discoveredNamespaces) goto cleanup;

Why not allocate this on the stack?