pgsql: ANSI-ify a few straggler K&R-style function definitions.

ANSI-ify a few straggler K&R-style function definitions.

We still had a couple of these left in ancient src/port/ files.
Convert them to modern style in preparation for switching to
a version of pg_bsd_indent that doesn't cope well with K&R style.

Discussion: https://postgr.es/m/16886.1558104483@sss.pgh.pa.us

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/da71f98efba9aed493a178aa29f25dbca7407eaf

Modified Files
--------------
src/port/crypt.c | 45 ++++++++++++---------------------------------
src/port/isinf.c |  8 ++++++--
2 files changed, 18 insertions(+), 35 deletions(-)