feat(tazjin/rlox): Implement simple arithmetic operators

Change-Id: I9873bcd281053f4e9820a5119f5992a0b8cb8cfc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2417
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>

users/tazjin/rlox/src/bytecode/chunk.rs

@@ -66,6 +66,7 @@ impl Chunk {
 
 /// Print a single disassembled instruction at the specified offset.
 /// Some instructions are printed "raw", others have special handling.
+#[cfg(feature = "disassemble")]
 pub fn disassemble_instruction(chunk: &Chunk, offset: usize) {
     print!("{:04} ", offset);