gdb configure updates

gdb configure updates

Now that the configury needed for the "common" and "target"
directories is in common.m4, some code in gdb's configure.ac is
redundant.

I ran this script after making an "ID" file using mkid:

   sed -n 's/^.*\(HAVE_[A-Z0-9_]*\).*$/\1/p' config.in |
   while read x; do
     echo ===== $x
     gid $x | egrep -v '^(testsuite|gnulib|common|target|gdbserver)/'
   done

This finds all the spots using HAVE_ defines, and, more importantly,
makes it clear which defines aren't used in the main parts of gdb.

From this I came up with this patch to remove all the unused bits.

There are a few that are subtly used -- for example the configure
script sometimes checks internal configure cache variables, meaning
some checks cannot be removed.

2013-11-08  Tom Tromey  <tromey@redhat.com>

	* configure, config.in: Rebuild.
	* configure.ac: Remove unused configury.