[xmlsec] loading crypto engines as plugins, build changes, et c.

[Jesse Pelton]

I think I'd make OpenSSL the default on Windows.  It's mature, well-tested,
and well-understood.  Secondarily, I'm using XMLSec specifically to get away
from Microsoft's "black box" CryptoAPI implementation, and others may have
similar motivation.  (I couldn't find a good way to set it up for use in an
ISAPI DLL called by Microsoft's Web server software.  But maybe Wouter's
implementation will address that issue somehow.)