MFC r265458:
Import George Wilson's change for Illumos #4730:

	4730 metaslab group taskq should be destroyed in metaslab_group_destroy()
	Reviewed by: Alex Reece <alex.reece@delphix.com>
	Reviewed by: Matthew Ahrens <mahrens@delphix.com>
	Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>

	Original author: George Wilson
MFC r265464:

Sort .ALLSRC before concatenating files together.  This makes sure that the
file are always built the same.

(Note that Header and Localstuff must appear first and in that order, the
sorting does not affect as a coincident effect).

Submitted by:	sjg