Which, I believe, indicates the externals need to be updated.

You could make your own local version and only use it if the Pd version is >= 0.52. As to how it should be done and where is the code? I dunno. I'd suggest looking at old versions of the Pd sources to see what the old function did, then see if there is a way to replicate it in whatever manner works with Miller's updates.

The functions in s_stuff.h have always been subject to change.