Verify that the Rust, C, and asm code all agree on alignments and other ABI issues for all types

[briansmith]

See #628 for background.

It's possible we might use a C compiler that has a different idea about alignment than the Rust compiler has. In particular, when the Rust compiler calls into C code, it might do so with objects that aren't aligned as much as the C code expects. Similarly with the asm code.

We already have some checks for primitive types using DEFINE_METRICS in C code and define_metrics_tests in Rust code. We could expand this to include all the non-primitive types shared between Rust and C too.

We should also see if we can somehow check "once and for all" that the ABIs match.

We might need to split checks/assurances for non-alignment ABI issues into a separate issue.

[briansmith]

Besides #628, see rust-lang/rust#45094 for more background.

[briansmith]

Closing as I believe this has been done for a long time.