This reverts commit 17f9b21c09aeed162ac8da5be6edab3a311d5556.
This is a partial unrevert. Qt 5.6 and Qt 5.7 remain building and
working. Qt 5.5 stays building but broken.
This reverts commit 7a9e04943dc82294037ec03e6eadf23d2933f821.
The commit in question breaks the patches to qtbase, causing the build to fail. An issue to track this feature will follow.