[Ur] error building in user directory

[Chris Casinghino]

This is a simple build error.  When building with a prefix in my home
directory (--prefix=~/usr), I get the following error during "make
install":

  ln -sf liburweb_fastcgi.so.1 /home/ccasin/usr/lib/urweb/../liburweb_fastcgi.so
  ldconfig
  /sbin/ldconfig.real: Can't create temporary cache file
/etc/ld.so.cache~: Permission denied
  make: *** [install] Error 1

I'm not sure how to tell ld not to put files in global directories,
but this isn't a problem when building other things for a single user.

Of course, "sudo make install" works fine, but I thought I'd report
the bug.

--Chris