This makes a few touch ups to benchmarks:
1. Add some regex-dna related benchmarks.
2. Change use of RUSTFLAGS="-C target-feature=+ssse3" to
RUSTFLAGS="-C target-cpu=native".
3. Switch order of parameters to regex-run-one benchmarking tool.
This uses the "Teddy" algorithm, as learned from the Hyperscan regular
expression library: https://01.org/hyperscan
This support optional, subject to the following:
1. A nightly compiler.
2. Enabling the `simd-accel` feature.
3. Adding `RUSTFLAGS="-C target-feature=+ssse3"` when compiling.
