Make patch-checking function able to raise a notice

Make patch-checking function able to raise a notice

There's probably a more elegant way to do this, but basic
testing with the following at least didn't throw an error:

SELECT evergreen.upgrade_deps_block_check('XXXX', NULL);

Also note that the CREATE OR REPLACE function calls will
fail on an existing database due to the changed return
type of the functions - so if this gets moved into its
own upgrade script, DROP FUNCTION calls will be
required.

Signed-off-by: Dan Scott <dscott@laurentian.ca>