Add obj_need_obj_free_p

[peterzhu2118]

We don't need to call obj_free on certain types of objects anymore including T_FLOAT, T_RATIONAL, T_COMPLEX, and T_OBJECT. It makes freeing those objects faster.

Benchmark:

i = 0
while i < 10_000_000
  Object.new
  i += 1
end

Before:

Time (mean ± σ):      1.435 s ±  0.013 s    [User: 1.706 s, System: 1.970 s]
Range (min … max):    1.418 s …  1.461 s    10 runs

After:

Time (mean ± σ):      1.230 s ±  0.027 s    [User: 1.335 s, System: 1.743 s]
Range (min … max):    1.206 s …  1.294 s    10 runs