pgsql: Remove excessively backpatched gitignore files

Remove excessively backpatched gitignore files

These caused directories from future releases to appear in the
backbranch tree.

Branch
------
REL8_2_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/335a00ab5708b9aaee179d0efa3b61f5549da4d3

Modified Files
--------------
contrib/btree_gin/.gitignore          |    1 -
contrib/citext/.gitignore             |    1 -
contrib/dict_int/.gitignore           |    1 -
contrib/dict_xsyn/.gitignore          |    1 -
contrib/pageinspect/.gitignore        |    1 -
contrib/pg_archivecleanup/.gitignore  |    1 -
contrib/pg_standby/.gitignore         |    1 -
contrib/pg_stat_statements/.gitignore |    1 -
contrib/pg_upgrade/.gitignore         |    1 -
contrib/test_parser/.gitignore        |    1 -
contrib/unaccent/.gitignore           |    1 -
src/backend/snowball/.gitignore       |    1 -
12 files changed, 0 insertions(+), 12 deletions(-)