Disabling lto in the benchmarks game

The maintainer of the benchmarks game has been running into bugs compiling the regex-dna benchmark on 32 bit with LTO enabled. He has said that he can selectively disable LTO per benchmark, but I think it is probably preferred that we either disable it everywhere or at least make it consistent across a specific benchmark. (The benchmarks for regex-dna currently have LTO enabled on x64 but disabled on x86. My understanding is that this isn't ideal.)

My preference is to disable LTO if it is causing the maintainer to run across bugs---it's just frustrating.

On the other hand, this is a benchmark, and presumably LTO is the "best that it will get."

@TeXitoi (who been managing the Rust benchmarks) is OK with this too: https://github.com/TeXitoi/benchmarksgame-rs/issues/3

Thoughts anyone? Basically, I'd like to build a consensus here so that we can say: "A preponderance of Rust users are OK (or not OK) disabling LTO, and we will not go back and forth on it."