cranelift: Remove booleans (#5031)

Remove the boolean types from cranelift, and the associated instructions breduce, bextend, bconst, and bint. Standardize on using 1/0 for the return value from instructions that produce scalar boolean results, and -1/0 for boolean vector elements.

Fixes #3205

Co-authored-by: Afonso Bordado <afonso360@users.noreply.github.com>
Co-authored-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Co-authored-by: Chris Fallin <chris@cfallin.org>

cranelift/wasm/src/environ/spec.rs

@@ -378,7 +378,7 @@ pub trait FuncEnvironment: TargetEnvironment {
         value: ir::Value,
     ) -> WasmResult<ir::Value> {
         let is_null = pos.ins().is_null(value);
-        Ok(pos.ins().bint(ir::types::I32, is_null))
+        Ok(pos.ins().uextend(ir::types::I32, is_null))
     }
 
     /// Translate a `ref.func` WebAssembly instruction.