Build libjs from source for now until the Perl threading problem can be reliably...

Build libjs from source for now until the Perl threading problem can be reliably tested

The previous commit changed JavaScript::SpiderMonkey to be built without
thread safety, but on Fedora we had been installing the js-devel package
(which was threaded). As you can't build a non-threaded
JavaScript::SpiderMonkey on top of a threaded libjs, for now we'll make
Fedora build a non-threaded libjs from source just like the other distros.

Note that the problem with threaded JavaScript::SpiderMonkey surfaced
on Debian Lenny when targeting holds. Lenny has libthreads-perl 1.71, but
a number of fixes have been committed to subsequent versions
(http://cpansearch.perl.org/src/JDHEDDEN/threads-1.82/Changes) - so
threading support might be reliable on more current distros. Once we
have a reliable test, we might be able to go back to the packaged
version of libjs.

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_2_1@19847 dcc99617-32d9-48b4-a31d-7c20da2025e4