ARM clockfix

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.

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.

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.

Fix for passing pointer to jack_intclient_t.

This code is now part of <jack/types.h>

Note that the -I option is still the correct thing to use if you want more control over setting up one of these clients.