pgsql: Allow multibyte characters as escape in SIMILAR TO and SUBSTRING

Allow multibyte characters as escape in SIMILAR TO and SUBSTRING.

Previously, only a single-byte character was allowed as an
escape. This patch allows it to be a multi-byte character, though it
still must be a single character.

Reviewed by Heikki Linnakangas and Tom Lane.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/8167a3883a3c49f2f77785f8e5f638920c9f14ef

Modified Files
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src/backend/utils/adt/regexp.c |   63 ++++++++++++++++++++++++++++++++++++----
1 file changed, 58 insertions(+), 5 deletions(-)