perf trace: Add helper for syscalls with a single strarray arg

In such cases just stating the (arg, name, array) is enough, reducing
the size of the syscall formatters table.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.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/n/tip-3k53p6dv2sh4ydsc5k5otoia@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>