Examples on how to test:
./configure --with-xml static
./configure --with-xml=/opt static
./configure --with-xml=shared shared
./configure --with-xml=shared,/opt shared
The difference between these two is that when the extension is shared, it
is not merged into libphpext.a. The shared extension is currently always
built. I can't find a way to do just one or the other with automake/libtool,
if someone has a clever idea, please come forward. :-)
"make install" installs the .so (as well as a lot of other cruft) in
$prefix/lib/php.
