Enable MPI module files #929
Description
Originally posted by @Carltoffel in #859 (comment) :
When I use the MPI metapackage with `use mpi`, I also have to use `build.external-modules = ["mpi"]`. Is this behaviour intended? Otherwise, I get:
+ which mpiexec
/usr/bin/mpiexec
<ERROR> *cmd_run* Targets error: Unable to find source for module dependency: "mpi" used by "app/main.f90"
In the example_packages directory, import mpif.h is used, which circumvents this. Which method is preferred?