[test] Missing Test Size for `SockAddr`

[ppenna]

Description

In the test_size_demi_sgarray_t() unit test function, we are relying on the compiler to compute the size of SockAddr.

This is against the idea of this test: ensuring that the structure matches a size that we want. This property is important to avoid UB when crossing language boundaries.

Code Snippets

demikernel/src/rust/runtime/types/memory.rs

Lines 71 to 85 in ffaf885

	fn test_size_demi_sgarray_t() -> Result<(), anyhow::Error> {
	// Size of a void pointer.
	const SGA_BUF_SIZE: usize = 8;
	// Size of a u32.
	const SGA_NUMSEGS_SIZE: usize = 4;
	// Size of an array of demi_sgaseg_t structures.
	const SGA_SEGS_SIZE: usize = mem::size_of::<demi_sgaseg_t>() * DEMI_SGARRAY_MAXLEN;
	// Size of a SockAddr structure.
	const SGA_ADDR_SIZE: usize = mem::size_of::<SockAddr>();
	// Size of a demi_sgarray_t structure.
	crate::ensure_eq!(
	mem::size_of::<demi_sgarray_t>(),
	SGA_BUF_SIZE + SGA_NUMSEGS_SIZE + SGA_SEGS_SIZE + SGA_ADDR_SIZE
	);
	Ok(())