plx 1.1.1

plx 1.1.1 is a code-only patch release (no catalog changes). It restores
compilation on PostgreSQL 13-15 and fixes several plxcobol bugs found in review.

Upgrade an existing install with:

ALTER EXTENSION plx UPDATE TO '1.1.1';

Fixed

• Compilation on PostgreSQL 13, 14, and 15. plx_strbuild.c included
  varatt.h unconditionally, but that header was only split out of postgres.h
  in PostgreSQL 16, so 1.1 did not build on 13-15. The full 9-suite regression
  now passes on PostgreSQL 13 through 18 (verified in CI).
• plxcobol crash (out-of-bounds read) on a body truncated at
  PERFORM VARYING ... UNTIL; it now errors cleanly.
• plxcobol ADD a b GIVING c and other multi-addend ADD/SUBTRACT forms
  were rejected; they are parsed as operand lists now.
• plxcobol multi-argument function calls (mod(a, b)) were broken because
  the tokenizer stripped commas everywhere; commas inside parentheses are kept.
• plxcobol GREATER/LESS ... OR EQUAL at the end of a condition, a PICTURE
  repeat-count overflow, and unterminated string handling.

Added

• Continuous integration (GitHub Actions) running the full suite on PostgreSQL
  13 through 18 (green).
• plxcobol coverage in the fuzzer and corpus runner.
• A PGXN META.json, and the plx-1.1.1.zip distribution attached to this
  release.

Compatibility

Builds and passes the full regression suite on PostgreSQL 13, 14, 15, 16, 17,
and 18.