framefilter: prevent row filter overlap race hazards
cmake: add xcode build folder
cmake: detect Xcode generator, avoid static lib failure
cmake: add Xcode hacks for YASM integration (is there a better way?)
ipfilter: remove two unused file-static functions

Xcode reported these as warnings; Xcode build is now 100% clean
build: remove obsolete test script
threading: use named semaphores for POSIX events

Mac OS X does not support unnamed semaphores.  It's not clear what the
performance implications of this are on Linux (or Mac).  Also, this method is
not very robust. If x265 crashes, it leaves named semaphores in the system until
the kernel is restarted.
cmake: set MACOS build flag on mac builds (fixes CPU count detection)