• Update GNU coreutils to the latest version 8.31
• Enable tests via our framework (set the TEST_TARGET)
• Remove MAKE_JOBS_UNSAFE which was added in r306718 (due to "help2man: can't get '--help' info from man/stty.td/stty") as it looks like this very error had been fixed long time ago, per their ChangeLog:
  
  2015-03-06 Padraig Brady <P@draigBrady.com>

build: fix make dependencies for test.1
In certain parallel build situations this would give the error:

	  help2man: can't get `--help' info from man/test.td/[
	  Makefile:14189: recipe for target 'man/test.1' failed

  That said, the port should have been jobs-safe for about four years
  now, but for some strange reason nobody had noticed that.

Approved by: maintainer