mail/msmtp: fix the TLS option

Part of commit 61d57c2657e1178dd763c8dd63503a9338525f47 was
converting from *_CONFIGURE_ON to *_CONFIGURE_WITH
for the TLS option. As it is a radio option, it means that one
of the options will be always disabled, resulting in adding
--without-tls to the CONFIGURE_ARGS, and no TLS support.

Fix by switching back to CONFIGURE_ON and bump PORTREVISION
to regenerate the package.

Reported by: Scott Robbins