Stop compiling builtins before embedding.

I was getting an error message about incompatible bytecode (I'm not sure what the exact message was) testing on a Windows 7 machine.  I think it's because of architectural differences between 64 bit Linux and 64 bit Windows.  This skips compiling and just embeds the whole builtin.lua.

Originally, I saw the 3.2 manual which stated the bytecode was fully portable, but on further investigation it seems that they've repeatedly reduced portability guarantees in successive versions.