libbeauty: Make the mmap_flags strarray visible outside of its beautifier

So that we can later use it with the strarray__strtoul_flags() routine
that will be soon introduced.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-vldj3ch8su6i20to5eq31e8x@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>