Arguments to format_plural() shouldn't be wrapped in t()

Trying to extract a translation template for dba.module gives errors about format_plural(). the args you pass in aren't themselves supposed to be wrapped in t(). attached patch for HEAD. backport required, since these are used on lines that changed for the t() placeholder changes, anyway. ;) I'm only really creating the issue for history and to let others know, no sense waiting for reviews/testing, etc.