MPAS framework updates don't rebuild cleanly.

[rljacob]

Situation: I have a fully coupled case I've already created on a local clone of master. Then I update master which includes some changes to mpas-framework. Doing "case.build" results in an error. Hear's an example when I did an update that included #6883

/lcrc/group/e3sm/jacob/scratch/chrys/Wne4latest/bld/cmake-bld/framework/mpas_io.f90(246): error #6404: This name does not have a type, and must have an explicit type.   [MPAS_IO_ADIOSC]
          ioformat /= MPAS_IO_ADIOSC) then
----------------------^
compilation aborted for /lcrc/group/e3sm/jacob/scratch/chrys/Wne4latest/bld/cmake-bld/framework/mpas_io.f90 (code 1)

Some part of the MPAS build is not correctly recognizing what all needs to be rebuilt based on which files changed. Easiest solution is to blow away the mpas build dirs in $EXEROOT .

Reproducer:
Do a hard reset of a clone to master 69546dc
./create_newcase --case CASEDIR --res ne4pg2_oQU480 --compset WCYCL1850NS; cd CASEDIR; ./case.setup; ./case.build
(Reset SRCROOT to latest master; update submodules) (cd back to CASEDIR)
./case.build

[jonbob]

@rljacob -- there are other mpas files where changes also don't get picked up correctly, most especially the component mct drivers