This add a test utility macro jit_function, which allows declaring jitted python functions inside rust test functions. Example:

let add = jit_function! { add(a:i64, b:i64) -> i64 => r##"
    def add(a: int, b: int):
        return a + b
"## };

The above define the python function add, which is compiled to bytecode at compile time. That bytecode is then jitted into native code at runtime(we could also do this a compile time in the future). The return value of the macro is a lambda with the signature fn(i64, i64) -> i64.

As part of that I refactored py_compile_bytecode into two different macros py_compile and py_freeze.