Port to Intel LLVM on Jet

[GeorgeGayno-NOAA]

DESCRIPTION OF CHANGES:

• Add build module for Intel LLVM. Build using LLVM is the default.
• Retain option to build using Intel Classic.
• Update all scripts to load the Intel LLVM build module.

TESTS CONDUCTED:

If there are changes to the build or source code, the tests below must be conducted. Contact a repository manager if you need assistance.

• Compile branch on all Tier 1 machines using Intel (Orion, Jet, Hera, Hercules and WCOSS2). Done using dbcaeca and Intel LLVM on Jet, Hercules, Hera and Orion. Done using dbcaeca and Intel Classic on Cactus.
• Run unit tests on Jet. Done using dbcaeca. All tests passed using Intel LLVM.
• Run consistency tests on Jet. The global_cycle, ocnice_prep, ice_blend, snow2mdl and weight_gen tests passed. The chgres_cube, grid_gen, and cpld_gridgen tests failed. However, differences from the baseline were not significant.

Other tests on Jet:

• The weight_gen and gdas_init utilities were successfully tested on Jet.
• A global C96 uniform grid was successfuly created on Jet.

DEPENDENCIES:

None.

DOCUMENTATION:

N/A

ISSUE:

Fixes #1009.