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/s390x/lower.rs

@@ -45,7 +45,6 @@ impl LowerBackend for S390xBackend {
             Opcode::Nop
             | Opcode::Copy
             | Opcode::Iconst
-            | Opcode::Bconst
             | Opcode::F32const
             | Opcode::F64const
             | Opcode::Vconst
@@ -100,10 +99,7 @@ impl LowerBackend for S390xBackend {
             | Opcode::BxorNot
             | Opcode::Bitselect
             | Opcode::Vselect
-            | Opcode::Breduce
-            | Opcode::Bextend
             | Opcode::Bmask
-            | Opcode::Bint
             | Opcode::Bitrev
             | Opcode::Clz
             | Opcode::Cls