updating configure.in(ac) for automake 1.14

This removes several obsolete commands from the configure.in file and
tries to get it back to the way it's currently used without breaking
anything.

The m4 files could be moved into their own directory, but right now
some (only the ones libtool doesn't download I think) are being shipped
with make dist and the others aren't.  I didn't want to touch any of
those in case their directories are hardcoded anywhere.

This can probably be backported to tacacs+ 4.0.4 without errors.  I
believe all the obsolete automake commands have been deprecated since at
least 2010 so most people should be safe, and those that don't have new
automake should be able to continue using the shipped configure file.

The main goal, aside from making sure things work is to regenerate
config.guess and config.sub since they're used to detect weird stuff and
apparently someone wanted to run the code on something weird.