Debug: Enable more LuaJIT features for debugging

Make it easy to use LuaJIT debugging features:

1. Zones: Enable separate profiling for each app (with -jp=z argument). (Example in commit c425770.)
2. LUAJIT_USE_PERFTOOLS: Show individual traces in Linux `perf top`
3. LUAJIT_USE_GDBJIT: Make traces visible to GDB.