Add fsevent_watch_guard support for 32bit kernels
Add fsevent_watch_guard support for 32bit kernels

Adds cflag '-arch i386' if `uname -a` reports a 32bit kernel
See: https://github.com/guard/guard/pull/206#
Telmate/rb-fsevent,thibaudgg/rb-fsevent,Telmate/rb-fsevent,Telmate/rb-fsevent,thibaudgg/rb-fsevent,thibaudgg/rb-fsevent