Clear flags that come from UFS when building as submodule

[kgerheiser]

Pull Request Summary

Fix ufs-weather-model integration with CMake build

Description

Conflicting flags from UFS would enter WW3 build. Check if building as subdirectory and then clear CMAKE_Fortran_FLAGS

Issue(s) addressed

Fix #627

Commit Message

Clear flags that come from UFS when building as submodule

Conflicting flags from UFS would enter WW3 build. Check if building as subdirectory and then clear CMAKE_<lang>_FLAGS

Check list

• [x ] Branch is up to date with the authoritative repository (NOAA-EMC) develop branch.
• [x ] Checked the checklist for a developer submitting to develop.
• [x ] If a version number update is required, checked the updating version number checklist.
• [ x] If a new feature was added, a regression test for testing the new feature is added.

Testing

@JessicaMeixner-NOAA tested the fix by running UFS wave tests

[JessicaMeixner-NOAA]

ufs-weather-model log file on gaea can be found here: https://github.com/JessicaMeixner-NOAA/ufs-weather-model/blob/feature/ww3-cmake/tests/RegressionTests_gaea.intel.log

the regression tests for WW3 are running now on hera

[JessicaMeixner-NOAA]

The ufs-weather-model regression tests as is passed on orion, hera, gaea and wcoss-dell.
https://github.com/jessicameixner-noaa/ufs-weather-model/tree/feature/ww3-cmake

The WW3 standalone tests are as expected as well:

**********************************************************************
********************* non-identical cases ****************************
**********************************************************************
mww3_test_03/./work_PR2_UQ_MPI_d2                     (8 files differ)
mww3_test_03/./work_PR3_UNO_MPI_d2_c                     (6 files differ)
mww3_test_03/./work_PR3_UNO_MPI_d2                     (10 files differ)
mww3_test_03/./work_PR2_UNO_MPI_d2                     (5 files differ)
mww3_test_03/./work_PR1_MPI_d2                     (12 files differ)
mww3_test_03/./work_PR3_UQ_MPI_d2_c                     (8 files differ)
mww3_test_03/./work_PR3_UQ_MPI_d2                     (8 files differ)
ww3_ta1/./work_UPD0F_U                     (0 files differ)
ww3_tp2.10/./work_MPI_OMPH                     (4 files differ)
ww3_tp2.16/./work_MPI_OMPH                     (2 files differ)
ww3_ufs1.3/./work_a                     (1 files differ)

@aliabdolali the full tests can be found here: /scratch2/NCEPDEV/climate/Jessica.Meixner/PR_WW3/pr629/regtests I'm having issues transferring them to post them here at the moment.

[JessicaMeixner-NOAA]

The ufs-weather-model existing wave regtests are now passing, the WW3 standalone regtests on hera also pass. @aliabdolali this is ready to be merged