Don't release context before calling swapbuffers

With this change Qt3D now displays something on windows too!

Change-Id: I2c29d1ece618720cfcfd2aac7a34e6d4bfebb11f
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Force creation of native window surface early on

Change-Id: I771ceac8306186d8fafa58042b5e40b63ab5f665
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>