Currently it's not possible to dump llvm-ir in release build. With this
patch we allow it with `--emit llvm-ir`. In debug build we dump clif
always as before.
Fixes#1020
Fixes#836
Benchmark #1: simple-raytracer/raytracer_cg_clif
Time (mean ± σ): 9.250 s ± 0.056 s [User: 9.213 s, System: 0.015 s]
Range (min … max): 9.151 s … 9.348 s 20 runs
Benchmark #2: simple-raytracer/raytracer_cg_clif_cold_separated
Time (mean ± σ): 9.179 s ± 0.101 s [User: 9.141 s, System: 0.016 s]
Range (min … max): 9.070 s … 9.473 s 20 runs
Summary
'simple-raytracer/raytracer_cg_clif_cold_separated' ran
1.01 ± 0.01 times faster than 'simple-raytracer/raytracer_cg_clif'
