Add OS X jenkins slave

Move git checkout to $WORKSPACE/src becaue we were creating an
install directory which collided with the INSTALL file on a
case-insensitive filesystem. Build the 5.0.x branch on OS X.
TS-2300: remove the HIT_EVACUATE build option

HIT_EVACUATE is always on, so there's no need for a build option.
TS-2301: replace CACHE_READY with CacheProcessor::IsCacheReady