Don’t try to get glyph names from ‘post’ table

We already have code to get the glyph names from FreeType/Core Text and
they do better job than us (e.g. read names from CFF table), and I doubt
the default implementation is ever executed, so lets just drop it.
XeTeX: extract etex_version.h from xetex.web

git-svn-id: svn://tug.org/texlive/trunk/Build/source@29225 c570f23f-e606-0410-a88d-b1316a301751