pgsql: Fix ALTER OPERATOR to update dependencies properly.

Fix ALTER OPERATOR to update dependencies properly.

Fix an oversight in commit 321eed5f0f7563a0: replacing an operator's
selectivity functions needs to result in a corresponding update in
pg_depend.  We have a function that can handle that, but it was not
called by AlterOperator().

To fix this without enlarging pg_operator.h's #include list beyond
what clients can safely include, split off the function definitions
into a new file pg_operator_fn.h, similarly to what we've done for
some other catalog header files.  It's not entirely clear whether
any client-side code needs to include pg_operator.h, but it seems
prudent to assume that there is some such code somewhere.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/0dab5ef39b3d9d86e45bbbb2f6ea60b4f5517d9a

Modified Files
--------------
src/backend/catalog/pg_operator.c            |   35 +++++++-----
src/backend/commands/operatorcmds.c          |    5 +-
src/include/catalog/pg_operator.h            |   17 ------
src/include/catalog/pg_operator_fn.h         |   34 ++++++++++++
src/test/regress/expected/alter_operator.out |   73 +++++++++++++++++++++++---
src/test/regress/sql/alter_operator.sql      |   41 +++++++++++++--
6 files changed, 163 insertions(+), 42 deletions(-)