Check that the plist doesn't reference the stage dir during stage-qa

> Running Q/A tests (stage-qa)

Error: '/usr/ports/www/claroline/work/.PLIST.mktmp' is referring to /usr/ports/www/claroline/work/stage

• Error code 1

Differential Revision: https://reviews.freebsd.org/D685
Reviewed by: bdrewery
With hat: portmgr