Declare cnt variable needed with ESMF_AWARE_THREADING

This was mistakenly removed in 4d9073d when cleaning up unused
variables.

Resolves #482

Author: billsacks

cesm/driver/esm.F90

@@ -877,6 +877,9 @@ subroutine esm_init_pelayout(driver, maxthreads, rc)
     character(len=5)               :: inst_suffix
     character(CL)                  :: cvalue
     logical                        :: found_comp
+#ifdef ESMF_AWARE_THREADING
+    integer                        :: cnt
+#endif
     integer :: rank, nprocs, ierr
     character(len=*), parameter    :: subname = "(esm_pelayout.F90:esm_init_pelayout)"
     !---------------------------------------