fix how the disassembler handles ja instructions
fix how the disassembler handles ja instructions

https://doc.rust-lang.org/std/fmt/trait.LowerHex.html says "For primitive signed integers (i8 to i128, and isize), negative values are formatted as the two’s complement representation."

As such, we can't rely on Rust's "+" formatting flag when writing instruction offsets.

qmonnet/rbpf