libXext/buildlink3.mk, now that it is included there.
Leave the places where its API version is set or variables from it
are used directly (about 3 packages).
Based on PR 39980 by John Maier.
Xhomer is a machine emulator for the Digital Equipment Corporation (DEC)
Pro 350 computer, a PDP-11-based machine that was sold in the early
to mid-'80's. Xhomer is based on the PDP-11 CPU core from the SIMH simulator,
and is written entirely in C.
