* build-aux/update-b4-copyright: Do not accept 2-digit UPDATE_COPYRIGHT_YEAR, which was not handled correctly. Don't accept a `[' in a b4_copyright argument. Format code more consistently. Don't assume b4*copyright never occurs.
* Makefile.am (update-b4-copyright): New target rule. * build-aux/local.mk (EXTRA_DIST): Add update-b4-copyright. * build-aux/update-b4-copyright: New. * data/yacc.c: Remove stray characters around b4_copyright invocations.