Build the tests on macOS and test TCG. HVF doesn't work in travis.

sieve tests pass but they might timeout in travis, they were left out
because of that.

Suggested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Message-Id: <20200901085056.33391-9-r.bolshakov@yadro.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>