Update zm_timer.h

As proposed on https://github.com/ZoneMinder/ZoneMinder/issues/170
Update zm_thread.h

As proposed on https://github.com/ZoneMinder/ZoneMinder/issues/170
Merge pull request #172 from raulcaj/patch-1

Solution for Issue #170
Tell Travis to skip building the modern branch for now [skip ci]
Proper checking for sys/syscall.h
Merge branch 'master' into cmake-testing
Added sys/syscall.h checking to cmake