tools lib traceevent: Factor out and export print_event_field[s]()

tools lib traceevent: Factor out and export print_event_field[s]()

The print_event_field() and print_event_fields() functions print basic
information of a given field or event without the print format.  They'll
be used by dynamic sort keys later.

Committer note:

Rename it to pevent_print_field[s]() to get proper namespacing, as
discussed with Steven Rostedt.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1450876121-22494-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>