pgsql: Make CREATE TYPE print warnings if a datatype's I/O functions ar

Make CREATE TYPE print warnings if a datatype's I/O functions are volatile.

This is a followup to commit 43ac12c6e6e397fd9142ed908447eba32d3785b2,
which added regression tests checking that I/O functions of built-in
types are not marked volatile.  Complaining in CREATE TYPE should push
developers of add-on types to fix any misdeclared functions in their
types.  It's just a warning not an error, to avoid creating upgrade
problems for what might be just cosmetic mis-markings.

Aside from adding the warning code, fix a number of types that were
sloppily created in the regression tests.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/465d7e1882bc1f316c7cb2a68e751c34b403e8d7

Modified Files
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src/backend/commands/typecmds.c                  |   46 ++++++++++++++++++++++
src/test/regress/expected/create_cast.out        |    4 +-
src/test/regress/expected/create_type.out        |    8 ++--
src/test/regress/input/create_function_1.source  |    8 ++--
src/test/regress/output/create_function_1.source |    8 ++--
src/test/regress/sql/create_cast.sql             |    4 +-
src/test/regress/sql/create_type.sql             |    8 ++--
7 files changed, 66 insertions(+), 20 deletions(-)