stored in malloc'd space, not in a static variable.  Otherwise environment
variable list is corrupted if libpq is dynamically unlinked...

Now indexes of pg_class and pg_type are unique indexes
and guarantee the uniqueness of correponding attributes.
heap_create() was changed to take another boolean parameter
which allows to postpone the creation of disk file.
The name of rd_nonameunlinked was changed to rd_unlinked.
It is used generally(not only for noname relations) now.
Requires initdb.

unreasonable amount of time to clean up after a vanished parser problem.
Don't call fireRIRonSubselect when we know there are no subselects,
either.

Apparently, back in the dim reaches of prehistory, the parser couldn't
be trusted to label Const nodes with the correct constbyval value ...
and someone preferred to patch around this in copyObject rather than
fix the problem at the source.  The problem is long gone, but the hack
lingered on.  Until now.

indexes to open.  Avoid unnecessary work in ExecCheckPerm, too.

make_const --- don't repeat cache searches that aren't needed.