rust: add a utility module for compile-time type checks

It is relatively common in the low-level qemu_api code to assert that
a field of a struct has a specific type; for example, it can be used
to ensure that the fields match what the qemu_api and C code expects
for safety.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/qemu-api/src/lib.rs

@@ -12,6 +12,7 @@ pub mod bindings;
 #[rustfmt::skip]
 pub mod prelude;
 
+pub mod assertions;
 pub mod bitops;
 pub mod c_str;
 pub mod callbacks;