Move parameter check into appropriate code section at the begin.

Freeprocs variable was obtained from nnodes, so check the value of nnodes at
the begin in the MPI_PARAM_CHECK code section instead as discussed at the
developer list.

cmr=v1.7.5:reviewer=jsquyres:subject=move parameter check to begin


jsquyres, please review this CMR. Thanks.
Omit usage of pre calculated prime numbers and factorize directly.

Optimization of the MPI_Dims_create function which omits the usage of pre
calculated prime numbers and factorize directly as discussed at the developer
list.

cmr=v1.7.5:ticket=4217:reviewer=jsquyres