perf trace: Add beautifier for clock_gettime's clk_id argument

perf trace: Add beautifier for clock_gettime's clk_id argument

Before:
0.030 ( 0.002 ms): 2571 clock_gettime(which_clock: 1, tp: 0x7f3b45729cd0 ) = 0

After:
0.030 ( 0.002 ms): 2571 clock_gettime(which_clock: MONOTONIC, tp: 0x7f3b45729cd0 ) = 0

v2: Update to use the STRARRAY option

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1379900700-5186-6-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>