perf tools: Create for_each_event macro for tracepoints iteration

Similar to for_each_subsystem and for_each_event in util/parse-events.c,
add new macro 'for_each_event' for easy iteration over the tracepoints
in order to be more compact and readable.

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1485862711-20216-2-git-send-email-treeze.taeung@gmail.com


[ Slight change to keep existing style for checking strcmp() return ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>