Mark failures in rr traces (JuliaLang#39630)

This makes it easy to navigate to failed test in long rr traces by setting a breakpoint in
`jl_breakpoint`. Longer term we may want to do something fancier to enable automation,
but hopefully this is at least makes it easier to debug traces from Julia CI.

stdlib/Test/src/Test.jl

@@ -553,6 +553,7 @@ function do_test(result::ExecutionResult, orig_expr)
  @assert isa(result, Threw)
  testres = Error(:test_error, orig_expr, result.exception, result.backtrace, result.source)
  end
+ isa(testres, Pass) || ccall(:jl_breakpoint, Cvoid, (Any,), result)
  record(get_testset(), testres)
 end