Use allocatable types in write_ocean_geometry_files

  Changed the declarations of the vardesc and fields arrays to allocatable in
write_ocean_geometry_files, primarily to get one of the TC test cases to run
properly with the gcc compiler by shifting the memory for these arrays from
stack to heap.  The reason why this change works is not clear.  Some comments
describing these variables were also added.  All answers are bitwise identical.

src/initialization/MOM_shared_initialization.F90

@@ -1194,17 +1194,18 @@ subroutine write_ocean_geometry_file(G, param_file, directory, geom_file, US)
   type(unit_scale_type), optional, intent(in) :: US        !< A dimensional unit scaling type
 
   ! Local variables.
-  character(len=240) :: filepath
+  character(len=240) :: filepath  ! The full path to the file to write
   character(len=40)  :: mdl = "write_ocean_geometry_file"
-  integer, parameter :: nFlds=23
-  type(vardesc) :: vars(nFlds)
-  type(fieldtype) :: fields(nFlds)
+  type(vardesc),   dimension(:), allocatable :: &
+    vars     ! Types with metadata about the variables and their staggering
+  type(fieldtype), dimension(:), allocatable :: &
+    fields   ! Opaque types used by MOM_io to store variable metadata information
   real :: Z_to_m_scale ! A unit conversion factor from Z to m
   real :: s_to_T_scale ! A unit conversion factor from T-1 to s-1
   real :: L_to_m_scale ! A unit conversion factor from L to m
   type(file_type) :: IO_handle ! The I/O handle of the fileset
+  integer :: nFlds ! The number of variables in this file
   integer :: file_threading
-  integer :: nFlds_used
   logical :: multiple_files
 
   call callTree_enter('write_ocean_geometry_file()')
@@ -1213,6 +1214,12 @@ subroutine write_ocean_geometry_file(G, param_file, directory, geom_file, US)
   s_to_T_scale = 1.0 ; if (present(US)) s_to_T_scale = US%s_to_T
   L_to_m_scale = 1.0 ; if (present(US)) L_to_m_scale = US%L_to_m
 
+
+  nFlds = 19 ; if (G%bathymetry_at_vel) nFlds = 23
+
+  allocate(vars(nFlds))
+  allocate(fields(nFlds))
+
   !   var_desc populates a type defined in MOM_io.F90.  The arguments, in order, are:
   ! (1) the variable name for the NetCDF file
   ! (2) the units of the variable when output
@@ -1244,13 +1251,12 @@ subroutine write_ocean_geometry_file(G, param_file, directory, geom_file, US)
   vars(18)= var_desc("dyCuo","m","Open meridional grid spacing at u points",'u','1','1')
   vars(19)= var_desc("wet", "nondim", "land or ocean?", 'h','1','1')
 
-  vars(20) = var_desc("Dblock_u","m","Blocked depth at u points",'u','1','1')
-  vars(21) = var_desc("Dopen_u","m","Open depth at u points",'u','1','1')
-  vars(22) = var_desc("Dblock_v","m","Blocked depth at v points",'v','1','1')
-  vars(23) = var_desc("Dopen_v","m","Open depth at v points",'v','1','1')
-
-
-  nFlds_used = 19 ; if (G%bathymetry_at_vel) nFlds_used = 23
+  if (G%bathymetry_at_vel) then
+    vars(20) = var_desc("Dblock_u","m","Blocked depth at u points",'u','1','1')
+    vars(21) = var_desc("Dopen_u","m","Open depth at u points",'u','1','1')
+    vars(22) = var_desc("Dblock_v","m","Blocked depth at v points",'v','1','1')
+    vars(23) = var_desc("Dopen_v","m","Open depth at v points",'v','1','1')
+  endif
 
   if (present(geom_file)) then
     filepath = trim(directory) // trim(geom_file)
@@ -1265,7 +1271,7 @@ subroutine write_ocean_geometry_file(G, param_file, directory, geom_file, US)
   file_threading = SINGLE_FILE
   if (multiple_files) file_threading = MULTIPLE
 
-  call create_file(IO_handle, trim(filepath), vars, nFlds_used, fields, file_threading, dG=G)
+  call create_file(IO_handle, trim(filepath), vars, nFlds, fields, file_threading, dG=G)
 
   call MOM_write_field(IO_handle, fields(1), G%Domain, G%geoLatBu)
   call MOM_write_field(IO_handle, fields(2), G%Domain, G%geoLonBu)
@@ -1300,6 +1306,8 @@ subroutine write_ocean_geometry_file(G, param_file, directory, geom_file, US)
 
   call close_file(IO_handle)
 
+  deallocate(vars, fields)
+
   call callTree_leave('write_ocean_geometry_file()')
 end subroutine write_ocean_geometry_file