Write to `ishape_last` by querying shapefile

So pass argument hshpc instead of `n_shapes`. Preparing to append to
`ishape_last.txt` instead of just creating `ishape_last.txt` with a
single line.

Inst_eddies/inst_eddies.f90

@@ -204,9 +204,9 @@ program inst_eddies
      end if
   end do
 
-  call write_aux(corner_deg, step_deg, nlon, nlat, n_cyclo, &
+  call write_aux(corner_deg, step_deg, nlon, nlat, hshpc_cyclo, &
        shpc_dir = "SHPC_cyclo")
-  call write_aux(corner_deg, step_deg, nlon, nlat, n_anti, &
+  call write_aux(corner_deg, step_deg, nlon, nlat, hshpc_anti, &
        shpc_dir = "SHPC_anti")
   CALL shpc_close(hshpc_cyclo)
   CALL shpc_close(hshpc_anti)

Inst_eddies/write_aux.f90

@@ -4,12 +4,15 @@ module write_aux_m
 
 contains
 
-  subroutine write_aux(corner_deg, step_deg, nlon, nlat, n_shapes, shpc_dir)
+  subroutine write_aux(corner_deg, step_deg, nlon, nlat, hshpc, shpc_dir)
 
     ! Write auxiliary files "grid_nml.txt" and "ishape_last.txt".
 
     ! Libraries:
     use jumble, only: new_unit
+    use shapelib_03, only: shp_get_info_03
+
+    use derived_types, only: shpc
 
     ! Note: we do not use assumed-shape arrays here for corner_deg and
     ! step_deg because of an internal compiler error of ifort
@@ -26,15 +29,16 @@ contains
     ! size of ssh array in input NetCDF, assuming no repeated point if
     ! the grid is global
 
-    integer, intent(in):: n_shapes
+    TYPE(shpc), intent(in):: hshpc
     character(len = *), intent(in):: shpc_dir
 
     ! Local:
     namelist /grid_nml/ corner_deg, step_deg, nlon, nlat
-    integer unit
+    integer unit, n_entities
 
     !--------------------------------------------------------------------
 
+    call shp_get_info_03(hshpc%extremum, n_entities)
     call new_unit(unit)
     open(unit, file = shpc_dir // "/grid_nml.txt", status = "replace", &
          action = "write")
@@ -43,7 +47,7 @@ contains
 
     open(unit, file = shpc_dir // "/ishape_last.txt", status = "replace", &
          action = "write")
-    write(unit, fmt = *) n_shapes - 1
+    write(unit, fmt = *) n_entities - 1
     close(unit)
 
   end subroutine write_aux