#i125921# fix autodetection of the OSX 10.10 SDK

which failed because the autodetection only worked with single-digit
minor-versions.

Patch-by: Thorsten Wagner <thorsten.wagner.4@gmail.com>
Found-by: Thorsten Wagner <thorsten.wagner.4@gmail.com>
Review-by: Herbert Duerr <hdu@apache.org>