Log message:
pkgclean: check that PKGSRCDIR is a valid directory

For those of us who have multiple pkgsrc trees, or move them around,
and forget the path gets hard-coded into the shell script, or make a
typo when supplying an alternate PKGSRCDIR, and then wonder why nothing
gets cleaned.

Log message:
all: replace SUBST_SED with the simpler SUBST_VARS

pkglint -Wall -r --only "substitution command" -F

With manual review and indentation fixes since pkglint doesn't get that
part correct in every case.

Log message:
pkgclean: Properly replace @SH@ in pkgclean

Most of the times setting NO_CONFIGURE is not needed and can badly
interact with SUBST framework like in this case as pointed out by
PR pkg/53606.

Fixes PR pkg/53606.

Log message:
*: Move SUBST_STAGE from post-patch to pre-configure

Performing substitutions during post-patch breaks tools such as mkpatches,
making it very difficult to regenerate correct patches after making changes,
and often leading to substituted string replacements being committed.

Log message:
Remove pkgviews: don't set PKG_INSTALLATION_TYPES in Makefiles.

Log message:
LICENSE=2-clause-bsd

Log message:
Just define PKGNAME and use it.

Log message:
Use Mt for email addresses.

Log message:
"user-destdir" is default these days

Log message:
Remove redundant NO_CHECKSUM and EXTRACT_ONLY definitions.