devel/massif-visualizer: re-add PORTREVISION
PORTREVSION was dropped in 2a6cfd50d085f1b42d2c32022dd5232c493c4c46 due
to the port using
CATEGORIES=kde-application
This category is only meant to be used by ports part of the KDE Gear
release package, i.e. using
DISTVERSION=${KDE_APPLICATIONS_VERSION}
Reported by: bofh