hard-code pft numbers in pftvarcon for default taper values

Temporary change, pending merge of IM4 updates. IM4
removed a lot of the hard-coded tests that looked
for particular pfts by their assigned number. this required
modifying the helper function "woody" to be a non-binary
(i.e., now 0 = herbaceous, 1 = woody tree, 2 = woody shrub),
but this updated function isn't available to IM3 currently.

components/elm/src/main/pftvarcon.F90

@@ -1042,7 +1042,9 @@ subroutine pftconrd
     if (.not. readv ) then
       taper(:) = 200._r8
       do i = 0, npft - 1
-        if (woody(i) == 2) taper(i) = 10.0_r8 ! shrubs
+        ! RPF 240331 - need to revisit this section when integrating with IM4,
+        ! to make consistent with attempt to remove hard-coded pft numbers.
+        if (i >= nbrdlf_evr_shrub .and. i <= nbrdlf_dcd_brl_shrub) taper(i) = 10.0_r8 ! shrubs
       end do
     end if