Fix build warnings (errors on CI) due to mmap flag rename and deprecation.

crates/jit/src/code_memory.rs

@@ -120,7 +120,7 @@ impl CodeMemory {
 
             if !m.is_empty() {
                 unsafe {
-                    region::protect(m.as_mut_ptr(), m.len(), region::Protection::ReadExecute)
+                    region::protect(m.as_mut_ptr(), m.len(), region::Protection::READ_EXECUTE)
                 }
                 .expect("unable to make memory readonly and executable");
             }