fc72b7ccd3
When parsing isa specific values we were accidentally discarding the value of the flag, and treating it always as a boolean flag. This would cause a `clif-util` invocation such as `cargo run -- compile -D --set has_sse41=false --target x86_64 test.clif` to be interpreted as `--set has_sse41` and enable that feature instead of disabling it.