* bjorn/stdlib/rand-export_seed/OTP-13162:
  Correct rand:export_seed/0 when there is no prior seed

According to the documentation, rand:export_seed/0 should return
'undefined' if the seed has not been intialized. However, it will
create and return a seed. That means that the following code
will not work as expected:

  case rand:export_seed() of
     undefined -> rand:seen({1,2,3});
     _ -> ok
  end,
  rand:uniform(Range)

Add parentheses around annotated type union elements in map pair
types. The bug was introduced in Erlang/OTP 18.0.

Print constraints as 'V :: T' rather than 'is_subtype(V, T)'.

erl_lint:format_error/1 would crash with a function error if
conflicting types were given. That was most easily noticed in the
shell:

  Eshell V7.0.3  (abort with ^G)
  1> <<0/integer-binary>>.
  *** ERROR: Shell process terminated! ***

Noticed-by: Aleksei Magusev

The test suite depended on the compiler to call
erl_lint:format_error/1 to ensure that format_error/1 was
covered. Unfortunately, though, if format_error/1 crashed
the compiler would catch the exception so that the test suite
would not notice it.

Add a smoke test of format_error/1 that will crash if there is
any problem with erl_lint:format_error/1.

The shell command 'rp' prints strings as lists of integers
when pretty printing of lists is 'false'.