CMake: MPI flags always added when OASIS is compiled

[MHBalsmeier]

Pull Request Summary

When compiling with CMake and the OASIS flag is included, MPI is always included in the CMakeLists.txt.

Description

This PR makes sure that when OASIS is enabled, MPI flags are automatically added, since OASIS always needs it.

• Mention any labels that should be added: bug
• Are answer changes expected from this PR? no

Issue(s) addressed

• fixes CMake build for ww3_tp2.14 fails due to missing MPI flags #1352

Commit Message

MPI flags always added when OASIS is compiled

Testing

• The compilation and execution of ww3_tp2.14 is successful now.

[mickaelaccensi]

SOUNDS GOOD

[JessicaMeixner-NOAA]

Thanks for the update!

Tests were as expected:

**********************************************************************
********************* non-identical cases ****************************
**********************************************************************
mww3_test_03/./work_PR1_MPI_e                     (1 files differ)
mww3_test_03/./work_PR3_UNO_MPI_e                     (1 files differ)
mww3_test_03/./work_PR2_UQ_MPI_e                     (1 files differ)
mww3_test_03/./work_PR2_UNO_MPI_d2                     (16 files differ)
mww3_test_03/./work_PR1_MPI_d2                     (12 files differ)
mww3_test_03/./work_PR3_UNO_MPI_d2_c                     (10 files differ)
mww3_test_03/./work_PR3_UQ_MPI_d2_c                     (16 files differ)
mww3_test_03/./work_PR3_UNO_MPI_d2                     (16 files differ)
mww3_test_03/./work_PR2_UQ_MPI_d2                     (15 files differ)
mww3_test_03/./work_PR3_UQ_MPI_e                     (1 files differ)
mww3_test_03/./work_PR3_UQ_MPI_d2                     (13 files differ)
mww3_test_09/./work_MPI_ASCII                     (0 files differ)
ww3_tp2.10/./work_MPI_OMPH                     (7 files differ)
ww3_tp2.16/./work_MPI_OMPH                     (4 files differ)
ww3_tp2.6/./work_ST4_ASCII                     (0 files differ)
ww3_ufs1.3/./work_a                     (3 files differ)

[JessicaMeixner-NOAA]

matrixCompFull.txt
matrixCompSummary.txt
matrixDiff.txt