add 'make bench' target for pastebin/parseable formatted results

[quentusrex]

Run a series of standard benchmarks to be able to compare performance on different hardware, and from release to release(or patch to patch).

[catamorphism]

#4515 will help with this.

[catamorphism]

I think this is "4, well-covered", not "1, well-defined". Re-nominating.

[graydon]

accepted for well-covered milestone

[pnkfelix]

part of #8058

[pnkfelix]

P-low.

[steveklabnik]

triage: this is an enhancement, nothing has really changed.

[steveklabnik]

triage: no changes

[alexcrichton]

This is a pretty old bug at this point, and we now have http://perf.rust-lang.org/ for tracking perf, so I'm going to close this.