pgsql: Add to_regprocedure() and to_regoperator().

Add to_regprocedure() and to_regoperator().

These are natural complements to the functions added by commit
0886fc6a5c75b294544263ea979b9cf6195407d9, but they weren't included
in the original patch for some reason. Add them.

Patch by me, per a complaint by Tom Lane. Review by Tatsuo
Ishii.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/dfc0219f649d5450a5e4d491dab1eeb23ac5530a

Modified Files
--------------
doc/src/sgml/func.sgml | 28 +++++++++--
src/backend/utils/adt/regproc.c | 71 ++++++++++++++++++++++++++++
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.h | 4 ++
src/include/utils/builtins.h | 2 +
src/test/regress/expected/regproc.out | 82 +++++++++++++++++++++++++++++++++
src/test/regress/sql/regproc.sql | 15 ++++++
7 files changed, 199 insertions(+), 5 deletions(-)