While on the subject of things that could make it or not into 9.5.?,
I see that 9.5.0 already adds PGDLLIMPORT on the global variable
creating_extension, but CurrentExtensionObject on the very next
line of extension.h still doesn't have it.
The simplest way I've come up with in Windows to identify the extension
being created is to create some temporary object, call
getExtensionOfObject() on it, then drop it. A bit circuitous when on
any other platform I can just look at CurrentExtensionObject....
-Chap