initialized in MOM_barotropic

2. Split the loop that addes Rayleigh drag term to [uv]_accel_bt, so that the if-block is now outside the loop

Merge main to dev/gfdl

  Created the new config_src directory tree structure, as agreed upon at
https://github.com/NOAA-GFDL/MOM6/discussions/1286, to eventually accomodate the
selection of different infrastructures.  No .F90 files are changed but there are
small changes to ac/configure.ac to accomodate the new structure while also
allowing for the old target to use the old structure.  All answers are bitwise
identical, and all MOM6-examples and TC tests are passing.

…leigh

Fix the bug that Rayleigh_[uv] was not initialized in MOM_barotropic

  Updated the MOM6/docs files and .gitlab-ci.yml to reflect the new config_src
directory structure.

…barotropic

- Use a new branch of MRS in the gitlab pipelines

- The job within the gitlab pipeline gnu:ice-ocean-nolibs had a modified
  search path but a "," instead of a "/" led to al caps being compiled
  and thus failure.

This patch removes the AC_CHECK_FILE autoconf macro which assigns a
default path to the MOM_memory.h file path.

This path was defaulting back to the old directory, and was added to
support the regression verification testing, but this is a regression
problem with should be handled by the regression, not the autoconf
configuration.

This will produce a regression test fail, but it not a cause for concern.

Remove AC_CHECK_FILE for legacy MOM_memory.h

This patch removes two lines where the target build (used for regression
testing) were using the active branch's configure.ac, which caused path
mismatches.  We now use our local autoconf configuration files.

This patch also fixes a typo in the source code dependencies of the
target repository.

The AC_CHECK_FILE for the solo driver has also beed removed, for the
same reason as the MOM_memory.h check.

Some comments were also added or reformatted to undocumented flags.

Testing: Target uses local autoconf

Hallberg noaa gfdl fms2

…ssingline

Fix a missing line regarding vel_underflow

Depth-integrated momentum budget diagnostics

Typo correction

FMS1 Framework integration

…20210308

this is corresponding to GFDL 20210308 main branch commit (hash # a4049e7)