Cranelift(Aarch64): Optimize lowering of icmps with immediates (#5252)

We can encode more constants into 12-bit immediates if we do the following
rewrite for comparisons with odd constants:

        A >= B + 1
    ==> A - 1 >= B
    ==> A > B

cranelift/codegen/src/isle_prelude.rs

@@ -90,6 +90,11 @@ macro_rules! isle_common_prelude_methods {
             0 == value
         }
 
+        #[inline]
+        fn u64_is_odd(&mut self, x: u64) -> Option<bool> {
+            Some(x & 1 == 1)
+        }
+
         #[inline]
         fn u64_sextend_u32(&mut self, x: u64) -> Option<u64> {
             Some(x as u32 as i32 as i64 as u64)