dynamic linking and libtool

[Tim Pierce <twp@skepsis.com>]

I've added a little magic to the dynamic module linking code in Guile
1.3a.  When Guile is checking for the presence of a shared library in
a module directory, if it happens to find a .la file in that
directory, it will look for the name of a shared library inside that
file.  If this file isn't found, it'll look instead for a .so file and
try to link that.

This should make it easier to write Guile modules with compiled
components and to build them with libtool.  Libtool is useful because
it eases the pain of trying to build a shared library that will work
on dozens of different platforms.  With this change, Guile should be
able to transparently load any shared library that was built with
libtool, as long as the module code is installed in a directory on
Guile's %load-path.

love, T.