Merge pull request #3096 from ESMCI/jgfouca/branch-for-acme-split-201…

…9-04-29

Jgfouca/branch for acme split 2019 04 29

Bug fixes:

Need consistent case for USE_CXX in Makefile (Restores cxxlib flag for PIO2).
Some E3SM components still can't build with -DDEBUG
Test suite: scripts_regression_tests.py
Test baseline:
Test namelist changes:
Test status: [bit for bit, roundoff, climate changing]

Fixes [CIME Github issue #]

User interface changes?:

Update gh-pages html (Y/N)?:

Code review: @jedwards4b