Fixes #3916: Move r29693 to v1.7 branch (orte_iof_base.output_limit is an unsigned type;)

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r29693 [[BR]]
orte_iof_base.output_limit is an unsigned type; just initialize it to INT_MAX

cmr=v1.7.4:reviewer=rhc
Fixes #3919: Move r29699 to v1.7 branch (practice defensive programming)

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r29699 [[BR]]
Per patch from Jeff, treat the case where someone transfers an archived file of an unknown type. This can't actually happen as this is on the receive end, and the error would have been treated and rejected on the send side. Still, practice defensive programming.

cmr:v1.7.4:reviewer=rhc:subject=Practice defensive programming
Fixes #3910: Move r29682 to v1.7 branch (Fix compiler warning.)

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r29682 [[BR]]
Fix compiler warning.

cmr=v1.7.4:reviewer=hjelmn