pgsql: Avoid fetching past the end of the indoption array.

Avoid fetching past the end of the indoption array.

pg_get_indexdef_worker carelessly fetched indoption entries even for
non-key index columns that don't have one. 99.999% of the time this
would be harmless, since the code wouldn't examine the value ... but
some fine day this will be a fetch off the end of memory, resulting
in SIGSEGV.

Detected through valgrind testing. Odd that the buildfarm's valgrind
critters haven't noticed.

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/80a96e066eecb6bd1788964b5911a405d932a784

Modified Files
--------------
src/backend/utils/adt/ruleutils.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)