LD_LIBRARY_PATH exorcism

LD_LIBRARY_PATH exorcism

Thanks to commit 6d510b8db, we now no longer need LD_LIBRARY_PATH
to be set for invoking the compiler.

Next, before we were taking the LD_LIBRARY_PATH variable and
turning it into a compile path, presumably to attempt to handle
the cases where we weren't getting the right -L flags.  Also
interacting with this was a while ago we weren't really doing
uninstalled libtool libraries correctly, which is probably
how hacks involving LD_LIBRARY_PATH crept into the scanner.

Just require that we're passed the right -L flags, and we
should be doing libtool libraries better now.