pgsql: meson: Change default of 'selinux' feature option to auto

meson: Change default of 'selinux' feature option to auto

There is really no reason for selinux to behave differently than other
options.

Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: /messages/by-id/20231103211601.bgqx3cfq6pz2lmjw@awork3.anarazel.de

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/c04f3de3dca3b54e16d7774885c8b64f90ca259b

Modified Files
--------------
meson_options.txt | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)