add TAGS target in testsuite

[Tom Tromey]

>>>>> "Pierre" == Pierre Muller <pierre.muller@ics-cnrs.unistra.fr> writes:

Pierre> $ etags --version
Pierre> Exuberant Ctags 5.8, Copyright (C) 1996-2009 Darren Hiebert

You need the "real" etags, not this one.

Pierre> etags --language=none --regex='/proc[ \t]+\([^ \t]+\)/\1/' \
Pierre>           `find ../../../src/gdb/testsuite -name '*.exp' -print`
Pierre> etags: Warning: "--language" option is obsolete; use "--language-force"
Pierre> instead
Pierre> etags: Unknown language "none" in "language" option

I think that the Emacs etags defines the etags interface.
If Exuberant Ctags is incompatible, then that is their bug.

I suppose one could write configury for this, but it seems like more
trouble than it is worth to me.

If you prefer, I can revert this patch.

Tom