Merge pull request #1520 in SNORT/snort3 from ~RUCOMBS/snort3:so_rulez to master

Merge pull request #1520 in SNORT/snort3 from ~RUCOMBS/snort3:so_rulez to master

Squashed commit of the following:

commit f07cb92074a0874b6f64008dcafd3ba716de877a
Author: russ <rucombs@cisco.com>
Date:   Sat Mar 30 14:03:48 2019 -0400

    so rules: fixup shutdown sequencing

commit 01db8beda055da0ac1f936d4252670cd185a6ec3
Author: russ <rucombs@cisco.com>
Date:   Sun Feb 17 13:06:34 2019 -0500

    so rules: use stub strictly as a key

commit 498dec668e51bdeaf9ddcb91767099f2e79b3ff8
Author: russ <rucombs@cisco.com>
Date:   Sat Feb 16 11:53:51 2019 -0500

    so rules: make plain stubs same as protected