Log Message:
pkgtools/pkglint: update to 22.2.6

Changes since 22.2.5:

A makefile that adds a _VARGROUPS section is partly considered part of
the infrastructure. It may define and use variables from its own
namespace. For example, devel/cmake/build.mk adds _VARGROUPS+=cmake,
thereby reserving the namespace '_CMAKE_*' for itself.

Dependencies in BUILDLINK_API_DEPENDS and BUILDLINK_ABI_DEPENDS that
contain unresolved variable expressions are no longer marked as
redundant. They were marked as redundant before because '$', when
interpreted as a package version, was smaller than 0.0.