app/internal/egl,app/internal/window: move Lock/Unlock methods

EGL contexts don't need locking, so their Lock and Unlock methods
are empty. Remove them and add them where necessary instead.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/window/egl_android.go

@@ -48,3 +48,7 @@ func (c *context) MakeCurrent() error {
 	}
 	return nil
 }
+
+func (c *context) Lock() {}
+
+func (c *context) Unlock() {}