[abstracting path prefixing]

>I agree that this is something that needs improvement, and I've mentioned it
>before.  It would be relatively easy (even if tedious to sweep through the
>code) to migrate this to an abstraction.

.... it's been on various todo lists since what, 1997?  :), and we
seem to be (slowly) getting there.  -current has a well-defined slot
for the prefix (if used, and a single set of ALT_ macros, rather than
a distinct set of macros for each emul.