selectively building with mpi

[Adam Mercer]

Hi

In one of our projects we have one code that can be built using
${MPICC} (if it is available), but not other codes. How can I specify
to use ${MPICC} for one code, but ${CC} for the others. Also if
${MPICC} is not found, by AX_MPI, the code can fall back to be built
using ${CC}?

So I guess I'm asking how to build one code using a different compiler
than the others?

Cheers

Adam