Use, together with etags.el, an optimised form of tags,

Use, together with etags.el, an optimised form of tags,
which are almost always unnamed.  etags.el looks for an explicit
tag name, then for an implicit one.  See make_tag for details.
The change is both forwards and backwards compatible.
(make_tag): New function (was the disabled function new_pfnote).
(make_C_tag): Use it.