Add feature patch for -tpg/-ntpg.

Add feature patch for -tpg/-ntpg.

This switch enables using Postgres' rules for using tabs vs spaces
in indents, to match the output of our old "entab" program.
The FreeBSD maintainer wants no part of this, so we'll have to carry
this as a forked patch.  (The alternative is to go over to use-tabs-
whenever-possible rules, but that would result in circa 10K lines of
invisible whitespace diffs in the PG sources, which seems like lots
more pain than is justified.)