slight comment fix in quadgk
lapack_size: version with slightly better generated code.
fix prevind (and thisind, nexting) for SubString, for #3710
Fix #3720
Adds a matmul performance test.

Gets the ball rolling on a BLAS performance testing suite.
Merge pull request #3722 from blakejohnson/matmul-perf

Adds a matmul performance test.
clean up state when wait() is interrupted. re-fixes #3373
Merge branch 'master' of github.com:JuliaLang/julia
First draft of codespeedization of test/perf.

To use, run `make codespeed` in `test/perf`
Update default unit titles
Expect env variables instead of Base.BUILD_INFO for now
Be a little more assertive with Curl and JSON