[PEAR][DB] Import some new commits

[PEAR][DB] Import some new commits
Patch submitted by XRevan86

[DB/pgsql.php] Change pg_exec to pg_query
Encouraged by http://php.net/manual/en/function.pg-query.php and enables
improved monitoring by New Relic (https://newrelic.com)
[DB.php] changed count to empty for php7.2
[DB/common.php] change to array cast for php72

From: https://github.com/pear/DB/
Commits: 7d0ddaff, d04a42a5 and ea9fff4a, respectively