perf tests: Add valid callback for parse-events test

perf tests: Add valid callback for parse-events test

Adding optional 'valid' callback for events tests in parse-events
object, so we don't try to parse PMUs, which are not supported.

Following line is displayed for skipped test:

  running test 52 'intel_pt//u'... SKIP

Committer note:

Use named initializers in the struct evlist_test variable to avoid
breaking the build on centos:5, 6 and others with a similar gcc:

  cc1: warnings being treated as errors
  tests/parse-events.c: In function 'test_pmu_events':
  tests/parse-events.c:1817: error: missing initializer
  tests/parse-events.c:1817: error: (near initialization for 'e.type')

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Kim Phillips <kim.phillips@arm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: http://lkml.kernel.org/r/20180611093422.1005-2-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>