pgsql: Be more wary in initdb's creation of platform-dependent collatio

Be more wary in initdb's creation of platform-dependent collations.

Discard any collation aliases that match the built-in pg_collation entries
(ie, "default", "C", "POSIX"). Such aliases would be refused by a CREATE
COLLATION command, but since initdb is injecting them via a simple INSERT,
it has to make the corresponding check for itself. Per Martin Pitt's
report of funny behavior in a machine that had a bogus "C.UTF-8" locale.

Also, use E'' syntax for the output of escape_quotes, as per its header
comment.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/853c1750f91feaa6a72b29ae683c955ab6f4df70

Modified Files
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src/bin/initdb/initdb.c | 25 ++++++++++++++++---------
1 files changed, 16 insertions(+), 9 deletions(-)