pgsql: Add btree_gist support for enum types.

Add btree_gist support for enum types.

This will allow enums to be used in exclusion constraints.

The code uses the new CallerFInfoFunctionCall infrastructure in fmgr,
and the support for it added to btree_gist in commit 393bb504d7.

Reviewed by Tom Lane and Anastasia Lubennikova

Discussion: http://postgr.es/m/56EA8A71.8060107@dunslane.net

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/f7946a92b689199cba64e7406a1c12d12637168a

Modified Files
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contrib/btree_gist/Makefile | 9 +-
contrib/btree_gist/btree_enum.c | 187 +++++++++
contrib/btree_gist/btree_gist--1.4--1.5.sql | 69 ++++
contrib/btree_gist/btree_gist.control | 2 +-
contrib/btree_gist/btree_gist.h | 3 +-
contrib/btree_gist/btree_utils_num.c | 2 +
contrib/btree_gist/data/enum.data | 595 ++++++++++++++++++++++++++++
contrib/btree_gist/expected/enum.out | 91 +++++
contrib/btree_gist/sql/enum.sql | 38 ++
doc/src/sgml/btree-gist.sgml | 2 +-
10 files changed, 991 insertions(+), 7 deletions(-)