YJIT: Remove UTF-8 BOM [ci skip]

/yjit/src/backend/x86_64/mod.rs Is also UTF-8 and it doesn't have the
marker. The standard recommends against it, so remove it.

yjit/src/codegen.rs

@@ -1,4 +1,4 @@
-// We use the YARV bytecode constants which have a CRuby-style name
+// We use the YARV bytecode constants which have a CRuby-style name
 #![allow(non_upper_case_globals)]
 
 use crate::asm::*;