pgsql: Make Bitmapsets be valid Nodes.

Make Bitmapsets be valid Nodes.

Add a NodeTag field to struct Bitmapset.  This is free because of
alignment considerations on 64-bit hardware.  While it adds some
space on 32-bit machines, we aren't optimizing for that case anymore.
The advantage is that data structures such as Lists of Bitmapsets
are now first-class objects to the Node infrastructure, and don't
require special-case code to handle.

This patch includes removal of one such special case, in indxpath.c:
bms_equal_any() can now be replaced by list_member().  There may be
more existing code that could be simplified, but I didn't look very
hard.  We also get to drop the read_write_ignore annotations on a
couple of RelOptInfo fields.

The outfuncs/readfuncs support is arranged so that nothing changes
in the string representation of a Bitmapset field; therefore, this
doesn't need a catversion bump.

Amit Langote and Tom Lane

Discussion: https://postgr.es/m/109089.1668197158@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5e1f3b9ebf6e51f2c60abe9aba969c28a3b0f6c6

Modified Files
--------------
src/backend/nodes/Makefile            |  1 +
src/backend/nodes/bitmapset.c         |  2 ++
src/backend/nodes/copyfuncs.c         |  6 ++++++
src/backend/nodes/equalfuncs.c        |  6 ++++++
src/backend/nodes/gen_node_support.pl |  1 +
src/backend/nodes/outfuncs.c          |  5 +++++
src/backend/nodes/read.c              | 30 +++++++++++++++++++++++++++++-
src/backend/nodes/readfuncs.c         |  7 ++++++-
src/backend/optimizer/path/indxpath.c | 28 ++++------------------------
src/include/nodes/bitmapset.h         |  5 +++++
src/include/nodes/meson.build         |  1 +
src/include/nodes/pathnodes.h         |  6 ++----
12 files changed, 68 insertions(+), 30 deletions(-)