Fixes #3654: Move r28717, r28718 to v1.6 branch (COMM_SPAWN/rsh fix)

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Custom patch from ticket based on:

r28717 [[BR]]
If the default hostfile is empty, we need to pickup all the known nodes, not just the head node.

cmr:v1.7.3:reviewer=jsquyres
cmr:v1.6.6:reviewer=jsquyres
Fixes #3657: Check all addresses in ifislocal

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Custom patch from ticket based on:

r28716 [[BR]]
If we enable ipv6, we resolve a hosts addresses and check them all against our local interfaces to determine if the given host is us. However, if we don't enable ipv6, we only checked the first address returned. This can cause us to incorrectly identify a hostname as "not us".

Make -disable-ipv6 behave the same as --enable-ipv6 by checking all the returned addresses.
Fixes #3668: Move r28787 to v1.6 branch

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r28787 [[BR]]
support for ConnectX3-Pro card. cmr:v1.7:reviewer=jsquyres cmr:v1.6:reviewer=jsquyres
Fixes #3691: Move VT v5.14.4.3 changes to v1.6

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r28924 [[BR]]
Changes to VT:
	- configure: Removed double slashes in path names which make trouble when building RPMs on Fedora (see #3688)
Add bullets for 1.6.6