runtime/pprof: create system test for blocking profile

[dvyukov]

Nobody knows whether it's working now or not.
Ideally the test must do end-to-end testing: build test, run test, run pprof, ensure
that the output is correct.
Similar tests are needed to CPU/memory profiler as well.

[rsc]

Comment 3:

Labels changed: added feature.

[dvyukov]

Comment 4:

Does label:Feature means that it must be done before feature freeze?
If so, I would expect adding tests to be a good task for feature freeze.

[rsc]

Comment 5:

As long as the test does not involve changes to the runtime, it is fine to do after the
freeze.

Labels changed: removed feature.

[dvyukov]

Comment 6:

This issue was closed by revision 2758101.

Status changed to Fixed.