pgsql: Follow-up fixes for SHA-2 patch (commit 749a9e20c).

Follow-up fixes for SHA-2 patch (commit 749a9e20c).

This changes the check for valid characters in the salt string to
only allow plain ASCII letters and digits. The previous coding was
locale-dependent which doesn't really seem like a great idea here;
moreover it could not work correctly in multibyte encodings.

This fixes a careless pointer-use-after-pfree, too.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Reported-by: Andres Freund <andres@anarazel.de>
Author: Bernd Helmle <mailings@oopsware.de>
Discussion: /messages/by-id/6fab35422df6b6b9727fdcc243c5fa1c667dd3b5.camel@oopsware.de

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/969ab9d4f5d141ac25db092a0e5cd004d3d60a60

Modified Files
--------------
contrib/pgcrypto/crypt-sha.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)