pgsql: psql: Fix tab completion for DROP INDEX CONCURRENTLY

psql: Fix tab completion for DROP INDEX CONCURRENTLY

psql offered CASCADE after DROP INDEX CONCURRENTLY and an index name,
even though CASCADE is not supported with CONCURRENTLY. Offer only
RESTRICT in this case, while retaining both CASCADE and RESTRICT
for ordinary DROP INDEX.

Backpatch to all supported versions.

Author: Sho Ito <i(dot)sho(dot)0628(at)gmail(dot)com>
Reviewed-by: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
Reviewed-by: Shihao Zhong <zhong950419(at)gmail(dot)com>
Reviewed-by: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Discussion: https://postgr.es/m/CAG7L5+7KXgvJUGCGXzyQrt7UysC9iytaYzx-7YyQTFYXjHVTWQ@mail.gmail.com
Backpatch-through: 14

Branch
------
REL_14_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/9a284cc75671aa0fdaea8f4e31ec8c1847685e59

Modified Files
--------------
src/bin/psql/tab-complete.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)