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 9 minutes and 30 seconds
latest
Status Job ID Name Coverage
  Build
passed #239183
mingw-build

00:09:13

passed #239181
shared-build

00:04:31

passed #239182
static-build

00:09:30