check mutable UnsafeCell; hack for AtomicBool::get_mut
check mutable UnsafeCell; hack for AtomicBool::get_mut

aidancully/rust,GBGamer/rust,rust-lang/miri,graydon/rust,GBGamer/rust,GBGamer/rust,rust-lang/miri,GBGamer/rust,graydon/rust,aidancully/rust,rust-lang/miri,rust-lang/miri,graydon/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,graydon/rust,tsion/miri,GBGamer/rust,aidancully/rust,aidancully/rust