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/codegen/src/isa/x64/abi.rs

@@ -260,13 +260,7 @@ impl ABIMachineSpec for X64ABIMachineSpec {
         // For integer-typed values, we always load a full 64 bits (and we always spill a full 64
         // bits as well -- see `Inst::store()`).
         let ty = match ty {
-            types::B1
-            | types::B8
-            | types::I8
-            | types::B16
-            | types::I16
-            | types::B32
-            | types::I32 => types::I64,
+            types::I8 | types::I16 | types::I32 => types::I64,
             _ => ty,
         };
         Inst::load(ty, mem, into_reg, ExtKind::None)