x86: Use short jumps in TIG::set_vtos_entry_points

Performance in -Xint mode seems to be bottlenecked on number of instructions executed, rather than particular instruction hotspots, which means code density is important.

There are forward branches in TemplateInterpreterGenerator::set_vtos_entry_points, which cannot be shortened by macro-assembler, unless we tell it specifically that the upcoming branch target would be within the 8-bit offset. Which it apparently is in this particular case, because there are just a handful of `push`-es between the jump and its target.