Merge pull request #3052 from ESMCI/maint-5.6

Merge Maint 5.6 back to master
Merge Maint 5.6 back to master that updates modules needed for
pgi on cheyenne

Test suite: scripts_regression_tests
Test baseline:
Test namelist changes:
Test status: bit for bit

Fixes [CIME Github issue #]

User interface changes?:

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

Code review:

config/cesm/machines/config_machines.xml

@@ -386,9 +386,9 @@ This allows using a different mpirun command to launch unit tests
 	<command name="load">pnetcdf/1.11.0</command>
       </modules>
       <modules mpilib="mpt" compiler="pgi">
-	<command name="load">mpt/2.15f</command>
-	<command name="load">netcdf-mpi/4.5.0</command>
-	<command name="load">pnetcdf/1.9.0</command>
+	<command name="load">mpt/2.19</command>
+	<command name="load">netcdf-mpi/4.6.1</command>
+	<command name="load">pnetcdf/1.11.0</command>
       </modules>
       <modules mpilib="openmpi">
 	<command name="load">openmpi/3.0.1</command>