cmd/gogio: add the first Windows e2e test via Wine

Since Wine is heavily tied to X11, we build its end-to-end test driver
on top of X11's. We use the same mechanism to start an X server, take
screenshots, and issue clicks.

Its only quirk is that it was difficult to get the screenshots to line
up with Gio's window. The comments cover what we ended up with. The
display dimensions are now part of driverBase, so that methods other
than Start can also use them - this is necessary for the wine driver to
crop screenshots.

We also use a sleep for now; a comment explains why, and a TODO is left
for future Dan to deal with. What we have now works, and I've spent
enough hours on this patch as it is.

Adding Wine to CI, and ensuring that the test passes there, is left for
a follow-up patch.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>

cmd/gogio/android_test.go

@@ -25,7 +25,7 @@ type AndroidTestDriver struct {
 
 var rxAdbDevice = regexp.MustCompile(`(.*)\s+device$`)
 
-func (d *AndroidTestDriver) Start(path string, width, height int) {
+func (d *AndroidTestDriver) Start(path string) {
 	d.sdkDir = os.Getenv("ANDROID_HOME")
 	if d.sdkDir == "" {
 		d.Skipf("Android SDK is required; set $ANDROID_HOME")