bump ruby-build version to fix compiler optimization bug

[mroth]

Addresses huge performance problems with compiled rubies not being properly optimized. Due to this bug, recent versions of ruby installed via boxen+rbenv+ruby-build are currently very slow -- this addresses that issue. (I know for certain with my testing it affects 2.0.0 and I believe also possibly 1.9.3)

See rbenv/ruby-build#335 and rbenv/ruby-build#340 and probably most importantly rbenv/ruby-build#351.

Here is a speed comparison with some trivial code on my system:

// ruby-2.0.0 unoptimized (current boxen default)
$ time ./fizzbuzz.rb 1000000 > /dev/null 
./fizzbuzz.rb 1000000 > /dev/null  2.12s user 0.06s system 98% cpu 2.220 total

// ruby-2.0.0 recompiled after ruby-build fix applied
$ time ./fizzbuzz.rb 1000000 > /dev/null 
./fizzbuzz.rb 1000000 > /dev/null  0.65s user 0.04s system 98% cpu 0.704 total

The performance difference is as much as 300-400%!

Note: Because of try_to_download_ruby_version.bash the precompiled ruby binaries that Boxen hosts on S3 will also need to be recompiled after this. I don't believe there is a way for me to do that via a pull request(?), so the Boxen maintainers will need to do so after merging this.

[mroth]

/cc @wfarr on this one since it's a large performance issue so it possibly needs his eyes.

[wfarr]

I'm working on rebuilding every version of 1.9.3 and 2.0.0 locally this evening to upload.

[mroth]

@wfarr cool, thanks. For future reference in case it ever comes up again, is that something I can do and add to a pull request? Or does that need to be done behind the scenes on some secret Github defrobulator?

[wfarr]

These tarballs are hosted on the GitHub S3. Naturally only GitHubbers have access to that. :)

[wfarr]

All versions managed in any ruby::* class rebuilt and uploaded.

Quick instructions to get upgraded here

[mroth]

🐢 ➡️ 🐎