pgsql: pgindent: Skip build directories automatically

pgindent: Skip build directories automatically

pgindent descended into build directories located inside the source
tree and reindented the generated files there, which is wasteful and
often makes pg_bsd_indent fail outright. This change automatically
recognizes build directories and skips them. This works for both
Meson build directories and Autoconf VPATH build directories. A build
directory named directly on the command line is still processed, on
the assumption that this was asked for on purpose.

Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Nazir Bilal Yavuz <byavuz81(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/fc77b35a-34c4-4229-82f1-8cf0ce67f276%40eisentraut.org

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/9dbc53591a2de03e0cfdab61a78726f8b2c29eef

Modified Files
--------------
src/tools/pgindent/pgindent | 32 ++++++++++++++++++++++++++++++--
src/tools/pgindent/pgindent.man | 5 +++++
2 files changed, 35 insertions(+), 2 deletions(-)