libffi fails to configure when path has spaces in it

[Joshua Minor]

This took me a while to track down, so I thought I'd share it with 
others.  If you happen to be in a directory that has spaces in the name 
(as is often the case on Mac OS X) then libffi's configure script 
fails.

% pwd
/Volumes/Kyoto_HD/Users/joshm/foo bar/pyobjc-1.0/libffi-src
% ./configure
creating cache ./config.cache
checking for Cygwin environment... no
checking for mingw32 environment... no
configure: error: can not find install-sh or install.sh in ../ ./../

This appears to be due to the fact that some $variables are not quoted 
properly, but the workaround it quite simple.  Just build in a path 
with no spaces.

-joshm