Fix failure of some headers to compile "standalone".

Tom Lane <tgl@sss.pgh.pa.us>

Commit: 678f5448c2d86976a98b402ef14482a8ba3b159b
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date: 2021-07-24T15:34:33Z
Releases: 15.0
Fix failure of some headers to compile "standalone".

Recently-added references to ParseState weren't covered by #include
references, creating unwanted ordering dependencies for users of
these headers.

Oversight in commit 2bfb50b3d.  Per headerscheck/cpluspluscheck.

Files