MFC r273768:

Remove the distinction between strings and numbers from ctld(8) yacc parser.
This fixes problems with passing strings that look like numbers to clauses
that expect strings; previously it caused syntax errors and had to be worked
by user, using quotes.  The workaround introduced in r267833 is no longer
neccessary.

Sponsored by:	The FreeBSD Foundation
MFC r273770:

Fix build after previous commit.  While here, improve error messages.

Sponsored by:	The FreeBSD Foundation