Hi,

I'm unable to get libtool 2.4.3 to build universally on OS X. It fails while calling lipo while attempting to build libltdl.la.

It looks like the `find` here is returning no files, which results in lipo being called with an output file but no input files: http://git.savannah.gnu.org/cgit/libtool.git/tree/build-aux/ltmain.in?id=5627a7f498e07a40b970c3a5ab5e74a5053e956f#n3243

This occurs when attempting to build universal i386/x86_64 for OS X 10.6 through 10.10, so it doesn't seem to be confined to a particular OS verison.