[gl2ps] Use OS X system GLUT even if X11 is installed

[ilove zfs]

https://github.com/Homebrew/homebrew/pull/50601/


The "bottle" build server happens to have X11 installed, but we'd prefer not to force an unnecessary X11 dependency on users. However, by default gl2ps will automatically link against X11's libglut.dylib if X11 happens to be installed. Therefore, I'm having to pass "-DGLUT_glut_LIBRARY=/System/Library/Frameworks/GLUT.framework" to cmake to avoid creating bottles that break on systems without X11. It would be nice if gl2ps used the system GLUT by default even if X11 happens to be installed without our having to manually intervene.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.geuz.org/pipermail/gl2ps/attachments/20160401/fb50d7c8/attachment.html>