Remove 'assert_c_type_sizes' test

The test I am removing fails on 32-bit ARM, as pointers are 4-byte aligned. `upb_MessageValue` is a union. The alignment of a union is the max. alignment of any of its fields. Among the fields are 8-byte types like u64 and thus `upb_MessageValue` is 8-byte aligned even on 32-bit ARM. 4 != 8 and it fails.

I am split on the usefulness of the test, as I find it somewhat unlikely to catch any divergence between the FFI and C types in the future. I can't imagine a practical scenario where upb_MessageValue would change in C code and this test would fail. IMO our actual unit & integration tests plus the IFTT lints are much better guards.

We could fix the test by testing the alignment of u64 instead of *const c_void, which is always 8 bytes on the hw platforms we care about.

PiperOrigin-RevId: 638976482

rust/upb.rs

@@ -767,24 +767,3 @@ pub unsafe fn upb_Map_InsertAndReturnIfInserted(
         upb::MapInsertStatus::OutOfMemory => panic!("map arena is out of memory"),
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use googletest::prelude::*;
-
-    #[test]
-    fn assert_c_type_sizes() {
-        // TODO: add these same asserts in C++.
-        use std::ffi::c_void;
-        use std::mem::{align_of, size_of};
-        assert_that!(
-            size_of::<upb_MessageValue>(),
-            eq(size_of::<*const c_void>() + size_of::<usize>())
-        );
-        assert_that!(align_of::<upb_MessageValue>(), eq(align_of::<*const c_void>()));
-
-        assert_that!(size_of::<upb_MutableMessageValue>(), eq(size_of::<*const c_void>()));
-        assert_that!(align_of::<upb_MutableMessageValue>(), eq(align_of::<*const c_void>()));
-    }
-}