Previously, we rejected map subscripts that are NULL, as well as
LIKE patterns that are NULL. General SQL expression evaluation
allows NULL everywhere, and doesn't raise errors - an expression
involving NULL generally yields NULL. Change the behavior to
follow that. Since the new behavior was previously disallowed,
no one should have been relying on it and there is no compatibility
problem.
Update the tests and note it as a CQL extension.
f5257533fd