Pass -Z verify-llvm-ir to tests that rely on it, to make sure they
pass regardless of the value of verify-llvm-ir in config.toml.
Also remove the 109681.rs test, because it is a duplicat of
common-linkage-non-zero-init.rs.
* The WASI targets deal with the `main` symbol a bit differently than
native so some `codegen` and `assembly` tests have been ignored.
* All `ignore-emscripten` directives have been updated to
`ignore-wasm32` to be more clear that all wasm targets are ignored and
it's not just Emscripten.
* Most `ignore-wasm32-bare` directives are now gone.
* Some ignore directives for wasm were switched to `needs-unwind`
instead.
* Many `ignore-wasm32*` directives are removed as the tests work with
WASI as opposed to `wasm32-unknown-unknown`.
Normally, variables with common linkage must be zero-initialized. In Rust,
common linkage variables that are not zero-initialized causes a crash in the
compiler backend.
This commit adds a test case to confirm this behavior, which will inform us if
it changes in the future.
