[CMake] testing for MPI_IN_PLACE

[Mark Abraham]

Hi,

When using MPI, our project needs to be able to test for the validity of 
MPI_IN_PLACE (http://redmine.gromacs.org/issues/594). Ideally we could 
use try_compile to compile a simple test program, however we need to be 
able to direct the use of the compiler information CMake found using the 
FindMPI module. I don't think this is possible at the moment.

Is there a recommended procedure? Should I open a try_compile feature 
request in the issue tracker?

Regards,

Mark