Don't warn about a function not invoked if the function is exported

[ale5000-git]

For bugs

• Rule Id (if any, e.g. SC1000): SC2329
• My shellcheck version (shellcheck --version or "online"): online
• The rule's wiki page does not already cover this (e.g. https://shellcheck.net/wiki/SC2086)
• I tried on https://www.shellcheck.net/ and verified that this is still a problem on the latest commit

Here's a snippet or screenshot that shows the problem:

#!/usr/bin/env bash

dummy_1=''
export dummy_1

dummy_2()
{
  :
}
export -f -- dummy

exit 0

Here's what shellcheck currently says:

SC2329 (info): This function is never invoked. Check usage (or ignored if invoked indirectly).

Here's what I wanted or expected to see:

Like variables, it would be nice if it doesn't warn also about function it they are exported.
One real life example may be this:

#!/usr/bin/env bash

_export_func_supported='false'
(
  dummy()
  {
    :
  }
  export -f -- dummy 2> /dev/null
) && _export_func_supported='true' || true

exit 0