* Renamed struct timer to struct minix_timer
* Renamed timer_t to minix_timer_t
* Ensured all the code uses the minix_timer_t typedef
* Removed ifdef around _BSD_TIMER_T
* Removed include/timers.h and merged it into include/minix/timers.h
* Resolved prototype conflict by renaming kernel's (re)set_timer
to (re)set_kernel_timer.
Change-Id: I56f0f30dfed96e1a0575d92492294cf9a06468a5