configure check changes

[Caleb Tennis]

I've committed changes to a bunch of configure.in.in's across the trunk 
(433982, 433984, 433988).  As noted in the log, the main thrust is to wrap 
autodetection of libraries needed by KDE inside of --with/--without 
statements, so that you can tell your KDE installation what features you 
do/don't want to use outside of it automatically finding them.  It is 
particularly important for source based distros.

Thiago noted that this should probably have gone here before the committal, 
and he's right, so I'm now presenting it here.  Please let me know if you 
have an issue with any of these so we can either fix them or revert if 
necessary.  They should be all be pretty transparent, except 433984 with 
modifies a few Makefile.am's.

Thanks,
Caleb