mail/mutt: Fix SASL option to not always disable SASL

With 60ba31d73e SASL_NONE_CONFIGURE_WITH however with it unchecked
--without-sasl was added. Always disabling sasl.

Use OPT_CONFIGURE_OFF and OPT_CONFIGURE_ON to make sure --without-sasl
isn't added when SASL_NONE is unchecked.

PR: 271395
Approved by: kh@panix.com (maintainer)