fix require_stdlib in Base.runtests error path

[IanButterworth]

  | ERROR: LoadError: Test run finished with errors
  | in expression starting at /Users/julia/.julia/scratchspaces/a66863c6-20e8-4ff4-8a62-49f30b1f605e/agent-cache/default-honeycrisp-R17H3W25T9.0/build/default-honeycrisp-R17H3W25T9-0/julialang/julia-master/julia-2efb19cc73/share/julia/test/runtests.jl:100
  | ERROR: MethodError: no method matching require_stdlib(::Module, ::Symbol)
  | The function `require_stdlib` exists, but no method is defined for this combination of argument types.
  |  
  | Closest candidates are:
  | require_stdlib(::Base.PkgId)
  | @ Base loading.jl:2401
  | require_stdlib(::Base.PkgId, ::Union{Nothing, String})
  | @ Base loading.jl:2401
  |  
  | Stacktrace:
  | [1] runtests(tests::String; ncores::Int64, exit_on_error::Bool, revise::Bool, seed::Nothing)
  | @ Base ./util.jl:698
  | [2] top-level scope
  | @ none:1

[vtjnash]

I beat you by mere minutes to this haha #53525