runtime/pprof: test that stack barriers never appear in profile
This adds a test that runs CPU profiling with a high load of stack
barriers and stack barrier insertion/removal operations and checks
that both 1) the runtime doesn't crash and 2) stackBarrier itself
never appears in a profile. Prior to the fix for gentraceback starting
in the middle of stackBarrier, condition 2 often failed.
Change-Id: Ic28860448859029779844c4bf3bb28ca84611e2c
Reviewed-on: https://go-review.googlesource.com/17037
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>