Replace mem::uninitialized<T>() with mem::MaybeUninit<T> #1025
Description
See the Rust 1.36 announcement concerning this change. uninitialized will be deprecated in 1.38, which means nightly already generates deprecation warnings. (CI tests nightly too.)
Fixing this should be easy enough (hint: "good first issue"), by running rg uninitialized and replacing all found uses with MaybeUninit (has nice examples showing equivalent code for uninitialized and MaybeUninit).