Until now sqrt(n) was missed as a factor for odd square numbers n. This
lead to suboptimal results of MPI_Dims_create for input numbers like 9,
25, 49, ... Fix the results by including sqrt(n) in the search for
factors.
Refs: #7186
Signed-off-by: Michael Lass <bevan@bi-co.net>
(cherry picked from commit 67490118adb8372d2aefe1d2d923432e51e100cd)
ff85c82151