Only use test wrapper-script if host is MinGW

Currently it fails if the executable extension is .exe, but wine isn't
available (e.g. on Cygwin)

Possibly the check to use this wrapper should be even more restrictive
e.g. checking if cross-building and/or if wine is available.
3 jobs for master in 5 minutes and 31 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #240091
mingw-build

00:04:30

passed #240089
shared-build

00:05:31

passed #240090
static-build

00:04:21