pgsql: psql: Rename results to result when only a single one is meant

psql: Rename results to result when only a single one is meant

This makes the naming more consistent with the libpq API and the rest
of the code, and makes actually supporting multiple result sets in the
future less confusing.

Discussion: https://www.postgresql.org/message-id/flat/db72fb98-9b43-d776-7247-6ed38f28e7c6%40enterprisedb.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/b9a3139397ff284cebc92fb008862ab902261883

Modified Files
--------------
src/bin/psql/command.c      |   6 +-
src/bin/psql/common.c       | 230 ++++++++++++++++++++++----------------------
src/bin/psql/crosstabview.c |  28 +++---
src/bin/psql/crosstabview.h |   2 +-
src/bin/psql/help.c         |   6 +-
src/bin/psql/settings.h     |   6 +-
src/bin/psql/tab-complete.c |   4 +-
src/bin/psql/variables.c    |   2 +-
8 files changed, 142 insertions(+), 142 deletions(-)