Never raise an error in configure_get_sdkroot
Never raise an error in configure_get_sdkroot

There may be times when it's appropriate to error out when the
requested SDK isn't present, but this isn't the right place for it,
since it can make Portfiles fail to parse entirely.

See: https://trac.macports.org/ticket/60465

neverpanic/macports-base,danchr/macports-base,danchr/macports-base,macports/macports-base,neverpanic/macports-base,macports/macports-base