Improve handling of getaddrinfo() on AIX (Tom)

This fixes a problem with starting the statistics collector, among other things.

Fix “failed to re-find parent key” errors in VACUUM (Tom)

Fix bugs affecting multi-gigabyte hash indexes (Tom)

Fix error when constructing an ARRAY[] made up of multiple empty elements (Tom)

to_number() and to_char(numeric) are now STABLE, not IMMUTABLE, for new initdb installs (Tom)

This is because lc_numeric can potentially change the output of these functions.

Improve index usage of regular expressions that use parentheses (Tom)

This improves psql \d performance also.