winevulkan: Add is_alias for VkFunctionPointer.

Signed-off-by: Georg Lehmann <dadschoorse@gmail.com>
Signed-off-by: Liam Middlebrook <lmiddlebrook@nvidia.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/winevulkan/make_vulkan

@@ -865,6 +865,8 @@ class VkFunctionPointer(object):
         text += ");\n"
         return text
 
+    def is_alias(self):
+        return False
 
 class VkHandle(object):
     def __init__(self, name, _type, parent, alias=None):