pgsql: Code review for 64-bit-large-object patch.

Code review for 64-bit-large-object patch.

Fix broken-on-bigendian-machines byte-swapping functions, add missed update
of alternate regression expected file, improve error reporting, remove some
unnecessary code, sync testlo64.c with current testlo.c (it seems to have
been cloned from a very old copy of that), assorted cosmetic improvements.

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/26fe56481c0f7baa705f0b3265b5a0676f894a94

Modified Files
--------------
src/backend/libpq/be-fsstubs.c | 60 ++++++------------
src/backend/storage/large_object/inv_api.c | 75 +++++++++++++++-------
src/backend/utils/errcodes.txt | 1 -
src/include/catalog/pg_proc.h | 2 +-
src/interfaces/libpq/fe-lobj.c | 87 ++++++++++----------------
src/test/examples/testlo64.c | 75 +++++++---------------
src/test/regress/input/largeobject.source | 2 +-
src/test/regress/output/largeobject.source | 2 +-
src/test/regress/output/largeobject_1.source | 82 ++++++++++++++++++++++++
9 files changed, 215 insertions(+), 171 deletions(-)