Qt in CI has been updated to 5.14 so we can drop these workarounds.
This reverts commit d18449c74327a8883ce0d7a80592255dbc70e864.
Revert "Qt 5.12, qhash"
This reverts commit 59ad852c02248857594301782449a168c5ecc627.
Revert "More for Qt 5.12"
This reverts commit 3e9f33bb3e58f03d200a628e48e9ca745628502e.
Revert "Allow building with Qt 5.12"
This reverts commit 54c6acadf2d46518d77bb1c44c6710970c9b1500.