Revert "Revert "Revert "mutex: dynamically disable mutex spinning at high load"""

This reverts commit 4e9d8f1a566bc9118d2d7bce5bcb733cff2f363c.
Revert "Revert "Revert "mutex: restrict mutex spinning to only one task per mutex"""

This reverts commit e56e53f57b26b8db4f4b254b21bafe2c18e09795.
Revert "Revert "Revert "mutex: Make more scalable by doing less atomic operations"""

This reverts commit 3b9458f4fa3c44909644bd4b960205b178cb71e7.
Revert "Revert "Revert "sched: don't call task_group() many times in set_task_rq()"""

This reverts commit 7a6e0157646e60edfa17ea8c78d216d6b3c11caa.