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/src/interpret.rs

@@ -156,14 +156,14 @@ mod test {
     fn nop() {
         let code = String::from(
             "
-            function %test() -> b8 {
+            function %test() -> i8 {
             block0:
                 nop
-                v1 = bconst.b8 true
+                v1 = iconst.i8 -1
                 v2 = iconst.i8 42
                 return v1
             }
-            ; run: %test() == true
+            ; run: %test() == -1
             ",
         );
         FileInterpreter::from_inline_code(code).run().unwrap()