util: matching a nil parameter with "any" type_check is ok!
util: matching a nil parameter with "any" type_check is ok!

* specl/util.lua (type_check): Lua treats deliberate `nil`
function arguments the same as omitted arguments, so don't raise
an error for a `nil` argument matched against an "any" type.

Signed-off-by: Gary V. Vaughan <f9023000f29773649f3850298becb9544b5fd6a9@gnu.org>

gvvaughan/specl