Fixes #4136: Move r30325 to v1.7 branch (Simplify and update hostfile handling)

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r30325 [[BR]]
Simplify and update hostfile handling to correctly support hostfiles that list nodes multiple times, once for each slot, and those that list a host once and include an explicit slot count. Eliminate support for mixing those two modes as this logic became just too complex when attempting to handle all the corner cases.

cmr=v1.7.4:reviewer=jsquyres


r30330 [[BR]]
A few corrections to hostfile parsing - thanks to Tetsuya Mishima for the review

Refs #4136


r30332 [[BR]]
Shift the verbose output a bit

Refs #4136
Fixes #4137: Move r30326 to v1.7 branch (Update platform file)

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r30326 [[BR]]
Update platform file

cmr=v1.7.4:reviewer=ompi-gk1.7
Fixes #4147: Move r30342 to v1.7 branch (Prevent integer overflow in datatype)

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r30342 [[BR]]
Prevent integer overflow in datatype creation. Patch based on 
Gilles Gouaillardet solution attached to ticket #4145.

Closes #4145.
cmr=v1.7.4:reviewer=ompi-rm1.7
cmr=v1.6.6:reviewer=ompi-rm1.6