Make mix tests optional

[davidozog]

This addresses #20 by adding --enable-mpi / --disable-mpi flag to configure.

[swx-jenkins2]

Can one of the admins verify this patch?

[mike-dubman]

@davidozog - could you please squash commits.
we are connecting jenkins CI to this project, hope it will be operational next week to smoke test & review it.
@MrBr-github

[jdinan]

@miked-mellanox You should be able to squash when you merge the commit by clicking the down arrow on the right side of the merge button and selecting "Squash and merge".

[davidozog]

@miked-mellanox Would you prefer that I "push --force" a squashed commit to this PR, open a new PR, or let you do the green-button "squash and merge"? I'm fine with whatever you prefer.

[ireed]

I was unaware that you were working on the MPI separation, and i was preparing a pull-request until i checked here.
I have a proposed version that auto-configures based on the existence/detection of -lmpi instead of depending on a hard-coded define. This method follows the style of the original architect(s).

ireed@aeadfd4

[jdinan]

I think the explicit --disable-mpi option will work better. It's common to have MPI installed in the development environment; however, the OpenSHMEM build may still not support mixed mode operation.

MPI also does not have a standard library name, so checking for libmpi is not sufficient to detect MPI. Something like this would be more robust:

AC_COMPILE_IFELSE([#include <mpi.h>
int main(void) { MPI_Init(NULL, NULL); MPI_Finalize(); return 0; }], ...)

[swx-jenkins2]

Can one of the admins verify this patch?

[mike-dubman]

ok to test

[mike-dubman]

bot:retest

[mike-dubman]

@davidozog - merge conflict