Fix filelib:wildcard/1,2 for patterns containing ".." and/or "@"

`..` was broken and only worked when it was used in the beginning
of the pattern before any wildcard characters. For example:

    1> filelib:wildcard("erts/..").
    ["erts/.."]

Using `..` preceded by wildcard characters would not work:

    1> filelib:wildcard("*/..").
    []

`@` is not a wildcard character but is used internally in `filelib` as
an escape character and was not handled as other literal
characters. That could lead to performance degradation as it disabled
an optimization of the matching of the literal prefix of a pattern. It
would also cause the following example to fail:

    1> filelib:wildcard("@/..").
    []

This commit corrects the handling `..` and also makes sure that the
use of `@` in a pattern does not degrade performance.

https://bugs.erlang.org/browse/ERL-1029

Code such as ets:fun2ms(fun({"foo" ++ X}) -> X end) works fine in
compiled code.  Let's make it work when fun2ms is invoked from the
shell as well.

* rickard/pcre-8.43/OTP-15889:
  Updated stdlib runtime dependency to erts
  Convert generated re replace and split tests from latin1 to UTF8
  Adjust generated re replacement and split tests
  Generate new re replacement and split tests using perl 5.22.1
  Update internal PCRE to version 8.43

`ordsets:union/1` is not especially efficient when calculating the
union of many ordsets. Rewrite it to use the highly optimized
`lists:umerge/1`.

* rickard/re-yield-unicode-validation/OTP-15836/ERL-876:
  Update runtime dependency from stdlib to erts
  Yield when validating UTF8 for long subject in re:run()
  Add yield_on_subject_validation() test

* rickard/re-global-unicode-validation/OTP-15831/ERL-876:
  Update runtime dependency from stdlib to erts
  Only validate subject once when global is used in re:run()
  Add global_unicode_validation() test