pgsql: #ifdef out some dead code in psql/mainloop.c.

#ifdef out some dead code in psql/mainloop.c.

This pg_send_history() call is unreachable, since the block it's in
is currently only entered in !cur_cmd_interactive mode. But rather
than just delete it, make it #ifdef NOT_USED, in hopes that we'll
remember to enable it if we ever change that decision.

Per report from David Binderman. Since this is basically cosmetic,
I see no great need to back-patch.

Discussion: https://postgr.es/m/HE1PR0802MB233122B61F00A15E035C83BE9C710@HE1PR0802MB2331.eurprd08.prod.outlook.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/3620569fecc6c2edb1cccfbba39b86c4e7d2faae

Modified Files
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src/bin/psql/mainloop.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)