Patch SharedLibLoader new exception and library path termination

[Tom Tromey]

Steve> Hey guy here is my first patch, If I mung up this submission
Steve> please let me know what I really need to do.

This patch looks fine.  The only thing you're missing is a ChangeLog
entry.  Could you write one?  That would be easiest.  Otherwise, I'll
try to get to it tomorrow.

I think this is ok for the 3.3 branch as well.  As far as I can tell
it won't affect binary compatibility.

Tom