pgsql: test_saslprep: Fix issue with copy of input bytea

test_saslprep: Fix issue with copy of input bytea

The data given in input of the function may not be null-terminated,
causing strlcpy() to complain with an invalid read.

Issue spotted using valgrind.

Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/09df9d75-13e7-45fe-89af-33fe118e797b@gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/5d35531af1840fdd8debfc1ff657643ddba029ab

Modified Files
--------------
src/test/modules/test_saslprep/test_saslprep.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)