Use different wrappers for MPI and non-MPI parts of tests.

tests/pio_write_deco2d_run.in

@@ -6,7 +6,7 @@ if [ @ENABLE_GRIB@ = yes ]; then
   suffix="${suffix-grb}"
   exec 5>&1 6>&2 >"$LOG" 2>&1
   ../libtool --mode=execute @MPI_LAUNCH@ -n ${mpi_task_num} \
-    ${tool_wrap} ./pio_write_deco2d ${pio_write_args}
+    ${tool_wrap_mpi} ./pio_write_deco2d ${pio_write_args}
   exec 2>&6 1>&5 5>&- 6>&-
   ../libtool --mode=execute \
     ${tool_wrap} ./cksum_read example_0.${suffix} example_0.cksum

tests/pio_write_run.in

@@ -16,7 +16,8 @@ for variation in "" $variations ; do
   exec 5>&1 6>&2 >"$LOG" 2>&1
   ../libtool --mode=execute \
     @MPI_LAUNCH@ \
-    -n ${mpi_task_num} ${tool_wrap} ./pio_write ${pio_write_args} ${variation}
+    -n ${mpi_task_num} ${tool_wrap_mpi} \
+    ./pio_write ${pio_write_args} ${variation}
   exec 2>&6 1>&5 5>&- 6>&-
   ../libtool --mode=execute \
     ${tool_wrap} ./cksum_read example_0.${suffix} example_0.cksum