pgsql: Fix misuse of "const" qualifier.

Fix misuse of "const" qualifier.

"const foo *" is quite different from "foo * const".
This code was evidently trying to avoid casting away
const from the arguments, but entirely failed to do so.

Per study of some buildfarm warnings from anole
(which unfortunately are mostly ignorable, since it
seems not to understand "restrict" very well).
I'm surprised though that nothing else has complained.

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/994d76707a254da6d03e389fa46141371a99e4e1

Modified Files
--------------
src/backend/partitioning/partbounds.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)