[OPT] Don't force return value of call to stack
[OPT] Don't force return value of call to stack

Benchmark #1: ./simple_raytracer_before
  Time (mean ± σ):     14.420 s ±  0.568 s    [User: 14.376 s, System: 0.026 s]
  Range (min … max):   13.730 s … 15.170 s    10 runs

Benchmark #2: simple_raytracer_after
  Time (mean ± σ):     13.679 s ±  0.576 s    [User: 13.628 s, System: 0.020 s]
  Range (min … max):   12.761 s … 14.552 s    10 runs

Summary
  './simple_raytracer_after' ran
    1.05 ± 0.06 times faster than './simple_raytracer_before'

aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust