Rust Slow Compilation

Reproducing rusterlium/rustler#299 with a simpler example.

Run the Benchmark

$ ./benchmark.sh

This will output a markdown table similar to the following:

commit	measurement	desc
d90890b	117.12	Initial slow example
03155fa	45.16	Impl on Struct instead of trait impl
3dd603f	49.97	Use use to make it look simpler
d650ffc	59.90	Remove ::rustler::Error
fd04a12	56.11	Remove Box
0f4eaf3	0.91	Replace match with map_err
dc7dd61	52.25	Remove &str from Err
c1dfe4f	57.43	Remove usize
0c09343	0.49	Try to replicate with a local crate for Decoder

Adding a new benchmark

benchmark.sh search for commits with a subject line prefixed with bench:. To add another benchmark, simply add a new commit with that prefix.