PR 3916
* buildrun.cxx (compile_pass): Add new autoconf options for checking
time related APIs.
* time.c (stp_time_t): Rename cpufreq to freq.
(__stp_get_freq): Rename from __stp_estimate_cpufreq. Use tsc_khz or
cpu_khz if it is available. Use itc_freq on ia64.
(__stp_ktime_get_real_ts): New function to get current kernel time.
(__stp_time_timer_callback): Call __stp_ktime_get_real_ts to get
base time.
(__stp_init_time): Ditto.
(__stp_constant_freq): New function to check the processor has
constant frequency timestamp counter.
(_stp_kill_time): Don't use the cpufreq notifier if the processor has
constant frequency timestamp counter.
(_stp_init_time): Ditto.
* autoconf-ktime-get-real.c : New file.
* autoconf-constant-tsc.c: Ditto.
* autoconf-tsc-khz.c: Ditto.