Some errors when I running setup_mac.sh, fixed

There Is some errors when I running setup_mac.sh in my mac book air.

1. QUICK_V3_ROOT has no value when running install_luajit.sh
2. "make no rule to make target" when running make in "LuaJIT-2.0.3/"
3. "permission denied" when running make in "LuaJIT-2.0.3/" after copying Makefile


So, 3 changes:

1. Export QUICK_V3_ROOT in setup_mac.sh for install_luajit.sh;
2. Copy Makefile to LuaJIT-2.0.3/src/ from luajit.org 2.0.3 version
3. add "sudo" before "make" in install_luajit.sh;