[COMMITTERS] pgsql: Add function to import operating system collations

Add function to import operating system collations

Move this logic out of initdb into a user-callable function.  This
simplifies the code and makes it possible to update the standard
collations later on if additional operating system collations appear.

Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Euler Taveira <euler@timbira.com.br>

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/aa17c06fb58533d09c79c68a4d34a6f56687ee38

Modified Files
--------------
doc/src/sgml/charset.sgml             |   2 +-
doc/src/sgml/func.sgml                |  40 ++++++++
src/backend/catalog/pg_collation.c    |  31 ++++++-
src/backend/commands/collationcmds.c  | 154 ++++++++++++++++++++++++++++++-
src/bin/initdb/initdb.c               | 166 +---------------------------------
src/include/catalog/catversion.h      |   2 +-
src/include/catalog/pg_collation_fn.h |   3 +-
src/include/catalog/pg_proc.h         |   3 +
8 files changed, 229 insertions(+), 172 deletions(-)