pgsql: Tweak collation setup for GIN index comparison functions.

Tweak collation setup for GIN index comparison functions.

Honor index column's collation spec if there is one, don't go to the
expense of calling get_typcollation when we can reasonably assume that
all GIN storage types will use default collation, and be sure to set
a collation for the comparePartialFn too.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/1766a5b63a950a667ed39c25256156bf366eb43c

Modified Files
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src/backend/access/gin/ginutil.c | 26 +++++++++++++++++++++++---
1 files changed, 23 insertions(+), 3 deletions(-)