Disable benchmark_effect_size test on Windows

As reported in bytecodealliance#178, the `benchmark_effect_size` test on Windows
occasionally fails with a strange error code and no output. This
conditional `#[ignore]` temporarily avoids the issue until we can figure
out what is going on.

crates/cli/tests/all/benchmark.rs

@@ -128,6 +128,7 @@ fn benchmark_summary() {
 }
 
 #[test]
+#[cfg_attr(target_os = "windows", ignore)] // TODO: https://github.com/bytecodealliance/sightglass/issues/178
 fn benchmark_effect_size() -> anyhow::Result<()> {
     // Create a temporary copy of the test engine.
     let test_engine = test_engine();