AppVeyor: use the default platform and configuration.
AppVeyor: use the default platform and configuration.

Indeed, to build/test so long on AppVeyor (slow queuing system and all
the jobs are run sequentially rather than in parallel as in Travis CI)
that it makes the whole CI a bit pointless.

mirams/opencor,mirams/opencor,Fairly/opencor,mirams/opencor,Fairly/opencor,Fairly/opencor,mirams/opencor,Fairly/opencor,mirams/opencor,Fairly/opencor