pgsql: Make contrib/pg_trgm also support regex searches with GiST index

Make contrib/pg_trgm also support regex searches with GiST indexes.

This wasn't addressed in the original patch, but it doesn't take very
much additional code to cover the case, so let's get it done.

Since pg_trgm 1.1 hasn't been released yet, I just changed the definition
of what's in it, rather than inventing a 1.2.

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/6f5b8beb64d481c28a483090d10099c8d619c797

Modified Files
--------------
contrib/pg_trgm/expected/pg_trgm.out | 132 ++++++++++++++++++++++++++++
contrib/pg_trgm/pg_trgm--1.0--1.1.sql | 4 +
contrib/pg_trgm/pg_trgm--1.1.sql | 6 ++
contrib/pg_trgm/sql/pg_trgm.sql | 23 +++++
contrib/pg_trgm/trgm.h | 5 +-
contrib/pg_trgm/trgm_gin.c | 3 +-
contrib/pg_trgm/trgm_gist.c | 152 +++++++++++++++++++++++++++-----
contrib/pg_trgm/trgm_op.c | 44 ++++++++++
contrib/pg_trgm/trgm_regexp.c | 14 ++--
doc/src/sgml/pgtrgm.sgml | 4 +-
10 files changed, 352 insertions(+), 35 deletions(-)