Restored local work array needed for ISOMIP_tracers

- For some unknown reason the declaration of a necessary work array
  was deleted. This code did not compile.

src/tracer/ISOMIP_tracer.F90

@@ -336,6 +336,7 @@ subroutine ISOMIP_tracer_column_physics(h_old, h_new,  ea,  eb, fluxes, dt, G, G
   real :: mmax
   real :: b1(SZI_(G))          ! b1 and c1 are variables used by the
   real :: c1(SZI_(G),SZK_(G))  ! tridiagonal solver.
+  real, dimension(SZI_(G),SZJ_(G),SZK_(G)) :: h_work ! Used so that h can be modified
   real :: melt(SZI_(G),SZJ_(G))  ! melt water (positive for melting 
                                  ! negative for freezing)
   integer :: i, j, k, is, ie, js, je, nz, m