MFC r264671:

MFV r264668:

4754 io issued to near-full luns even after setting noalloc threshold
4755 mg_alloc_failures is no longer needed
MFC r264740:

Use case insensitive match in portsnap.

PR:		bin/186510
Submitted by:	olli
MFC r264835: MFV r264829:

3897 zfs filesystem and snapshot limits
MFC r264836: MFV r264830:

4745 fix AVL code misspellings
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