Fix process name sentinel value in 32 bit and big endian systems

[jsquyres]

Per the following, we currently have a problem with the dynamic add procs behavior on 32 bit and big endian systems:

• ompi: temporarily disable dynamic add_procs on big-endian and 32-bit #1349: ompi: temporarily disable dynamic add_procs on big-endian and 32-bit
• Disable dynamic add procs for 32 bit and big endian environments #1348: Disable dynamic add procs for 32 bit and big endian environments
• Topic/sentinel proc name conversion #1345: Topic/sentinel proc name conversion

Per discussion on 9 Feb 2016 webex, we decided to simply disable dynamic add procs behavior on 32 bit and big endian systems for v2.0.0, and spend a little time thinking about / implementing a better long-term solution (that includes support for 32 bit and big endian systems). We may even discuss this at the face-to-face developer meeting in Dallas.

This issue is being opened to track the problem (in case #1349 is not where we end up solving the issue).