configure/Makefile: remove unused $LIBS and $LDFLAGS complications
configure: turn off automatic searches through non-standard directories

configure will no longer check for the existence of extra include, lib
and bin directories in /usr/pkg /sw /opt /opt/local /usr/local.

The check was not done in a particularly sensible manner and there are
now no mandatory dependencies that not shipped in the main system trees
on virtually every system in existence.

If building with Fink, follow these directions as suggested by the fink
project:
  http://www.finkproject.org/faq/usage-general.php#compile-myself

Closes #1185, and closes #1186.