cad/openvsp: fix build on CURRENT

• Pet portlint, USE_* comes before USES
• Bump PORTREVISION

On -CURRENT, gcc can not compile cad/openvsp. We switch to clang but need an
additional patch in the port, otherwise clang 5.0.0 r312293 and earlier crashes.

This patch will be removed if/when clang compiles clean the port.

This update is based on a patch by dim@

For details, see: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=221588

PR: 222001
Submitted by: Fernando Apesteguia <fernando.apesteguia@gmail.com> (maintainer)