Log Message:
pkgtools/pkglint: update to 21.3.1

Changes since 21.3.0:

When checking a standalone makefile fragment, pkglint reports redundant
variable declarations.

In pathname patterns, spaces and other escaping is allowed. This is
needed for devel/meson. While here, register MESON_REQD.

Adjust to the removal of SHA1 for distfiles. Only RMD160, SHA512 and
Size remain now. Patches continue to use SHA1 since they don't come
via untrusted paths.