pgsql: Force strings passed to and from plperl to be in UTF8 encoding.

Force strings passed to and from plperl to be in UTF8 encoding.

String are converted to UTF8 on the way into perl and to the
database encoding on the way back. This avoids a number of
observed anomalies, and ensures Perl a consistent view of the
world.

Some minor code cleanups are also accomplished.

Alex Hunsaker, reviewed by Andy Colson.

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=50d89d422f9c68a52a6964e5468e8eb4f90b1d95

Modified Files
--------------
doc/src/sgml/plperl.sgml | 8 ++
src/pl/plperl/SPI.xs | 52 ++++++---
src/pl/plperl/Util.xs | 66 +++++-----
src/pl/plperl/plperl.c | 260 +++++++++++++++++++++++-----------------
src/pl/plperl/plperl_helpers.h | 69 +++++++++++
5 files changed, 295 insertions(+), 160 deletions(-)