* src/vm/jit/builtin.hpp (builtintable_entry): Added function pointer to

* src/vm/jit/builtin.hpp (builtintable_entry): Added function pointer to
fast-path emitter. At the moment we have lock fast-path on x86_64.
* src/vm/jit/builtin.cpp: Builtin table now needs emit-common.hpp included.
* src/vm/jit/builtintable.inc: Adapted to above change.
* src/threads/lock.hpp: Moved builtin function defines to where they belong.
* src/vm/jit/codegen-common.cpp (codegen_emit): Added preliminary fast-path
generation implementation. Yet to be fully optimized.
* src/vm/jit/emit-common.hpp: Added prototypes for lock fast-path emitters.
* src/vm/jit/x86_64/emit.c: Added stubs for lock fast-path emitters.