Fix libjpeg-turbo OSX 10.9 test (fails on non-OSX OSes).

This fixes a recently-introduced bug in the buildme.sh script which causes it to fail on non-OSX machines. The problem is that $OSX_VER can be empty, which causes test to fail.

I had to run this because I recently upgraded my x86_64 Linux box from Fedora 17 to Fedora 19 and needed x86_64 versions for the DSOs for Perl 5.16.