perf stat: Avoid segfaults caused by negated options

Some 'perf stat' options do not make sense to be negated (event,
cgroup), some do not have negated path implemented (metrics). Due to
that, it is better to disable the "no-" prefix for them, since
otherwise, the later opt-parsing segfaults.

Before:

  $ perf stat --no-metrics -- ls
  Segmentation fault (core dumped)

After:

  $ perf stat --no-metrics -- ls
   Error: option `no-metrics' isn't available
   Usage: perf stat [<options>] [<command>]

Signed-off-by: Michael Petlan <mpetlan@redhat.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
LPU-Reference: 1485912065.62416880.1544457604340.JavaMail.zimbra@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>