Expand description
C types.
Avoid using the libc crate to get C types since libc doesn’t support
all the targets we need to support. It turns out that the few types we need
are all uniformly defined on the platforms we care about. This will
probably change if/when we support 16-bit platforms or platforms where
usize and uintptr_t are different sizes.
TODO(MSRV-1.64): Use core::ffi::{c_int, c_uint}, remove the libc
compatibility testing, and remove the libc dev-dependency.