Don't rely on CPU cycles to measure time.

We have a proper clocksource in the kernel, use this instead.

This commit also fixes jackd on ARM boards with newer Linux kernels
where /proc/cpuinfo has changed.
Make -c c an alias for -c s

The cycle counting clock is no longer supported. For backwards
compatibility with scripts, allow the user to request the cycle clock on
the command line, but use the system clock instead.
Remove cycles from the list of allowed clock sources
Don't check for CPU scaling anymore

Without cycle counting, CPU scaling isn't necessarily bad anymore, so we
don't have to worry the user.

The purpose of this commit is to get rid of JACK_TIMER_CYCLE_COUNTER.
Drop obsolete cycle counter option in libjack
Drop JACK_TIMER_CYCLE_COUNTER altogether
Merge pull request #10 from adiknoth/arm-clockfix

ARM clockfix