Fixes #4570: Move r31535 to v1.8 branch (pml/ob1: fix heterogeneous support when)

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r31535 [[BR]]
pml/ob1: fix heterogeneous support when using the send_inline optimization

We will track #4568 from the 1.8 CMR.

Closes #4568

cmr=v1.8.2:reviewer=jsquyres
Fixes #4601: Move r31635 to v1.8 branch (Datatype with count of zero)

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r31635 [[BR]]
Datatype with count of zero do not generate traffic in the type map, nor
have any impact on the type signature.

Fixes #4597.
cmr=v1.8.2:reviewer=ompi-rm1.8
Fixes #4605: Move r31683 to v1.8 branch (hwloc: commit minor bug fix)

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r31683 [[BR]]
hwloc: commit minor bug fix from hwloc git

Bring down 3aa0ed6 from the hwloc v1.7 branch: Stevens says we should
GETFD before we SETFD, so we do

cmr=v1.8.2:reviewer=rhc
Fixes #4607: Move r31687 to v1.8 branch (usnic: fix connectivity checker timeout)

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r31687 [[BR]]
usnic: fix connectivity checker timeout

Fix mismatch between the MCA param (which expresses the timeout in
*mili*seconds) and the struct timeval timeout (which expresses the
timeout in *micro*seconds).

Reviewed by Dave Goodell

cmr=v1.8.2:reviewer=ompi-rm1.8
Fixes #4608: Move r31688 to v1.8 branch (usnic: reduce sizeof(ompi_btl_usnic_addr_t) to 56)

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r31688 [[BR]]
usnic: reduce sizeof(ompi_btl_usnic_addr_t) to 56 bytes
    
Trivial struct re-ordering to eliminate holes in the middle of the
struct (although there's still a hole at the end) and reduce the
overall size of the struct from 64 to 56 bytes.  Also change mtu from
int to uint16_t; there was no need for it to be that large.

Reviewed by Dave Goodell

cmr=v1.8.2:reviewer=ompi-rm1.8
Fixes #4609: Move r31689 to v1.8 branch (usnic: ensure that procs agree)

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r31689 [[BR]]
usnic: ensure that procs agree on use_udp value
    
Add the component use_udp value into the modex.  If my component's
use_udp value doesn't agree with the use_udp value from a peer's modex
data, print a helpful message and disqualify the usnic BTL (the usnic
BTL will not be used).  This prevents accidental customer
misconfigurations.

Reviewed by Dave Goodell

cmr=v1.8.2:reviewer=ompi-rm1.8