Proper handling of GET request with body in case of chained redirections

 
QTBUG-112871 has introduced GET requests with body. However, in case of chained redirections the current implementation is incorrect.

For example, in case of a 301 (moved permanently) we are clearing both the body and the headers. If this is followed by a 308 (permanent redirect) the headers are reconstructed from the original request, but the body is not. This is wrong, the headers and the body should be kept in sync. Specifically, after we have cleared the body and headers we should never restore them.