Get rid of uses of mem::uninitialized

[RalfJung]

007d87f added a bunch of allow(deprecated) because there are still a few places where we use mem::uninitialized. These should all be fixed, to remove the allow (and hopefully prevent other deprecated methods from being used there).

• SGX
• libterm
• librustc_codegen_llvm
• std::io::util
• CloudAbi layout tests (src/libstd/sys/cloudabi/abi/cloudabi.rs)
• rustc tests

Cc @EdSchouten for CloudAbi, @jethrogb for SGX.

[JulianGindi]

Going to take a stab at addressing this issue if that's all right.

[JulianGindi]

Actually looks like some of this was already handled.

[RalfJung]

The SGX and libterm and codegen ones have been handled. CloudAbi and std::io::util remain open as far as I can see.

[JulianGindi]

CloudAbi and std::io::util remain open as far as I can see.

Ah, gotcha. Will take a crack at it. Thanks!

[jethrogb]

And what about all the tests?