Make 'pio_write_run' responsible for skipping tests for disabled file formats.

tests/pio_cksum_cdf.in

 #!@SHELL@
 @USE_MPI_FALSE@exit 77
-@ENABLE_NETCDF_FALSE@exit 77
 
 LOG=pio_cksum_cdf.log
 
-if test 'x@ENABLE_NC4' = xyes; then
-  suffix=nc4
-  mpi_task_num=7
-  pio_write_args="-f $suffix -w 3 -qtaxis-type=relative"
-  . ./pio_write_run
-fi
+suffix=nc4
+mpi_task_num=7
+pio_write_args="-f $suffix -w 3 -qtaxis-type=relative"
+(. ./pio_write_run) || test $? -eq 77 || exit 1
 
 mpi_task_num=8
 suffix=nc2
 pio_write_args="-f $suffix -w 3 -qtaxis-type=relative"
-. ./pio_write_run
+(. ./pio_write_run) || test $? -eq 77 || exit 1
 
 mpi_task_num=5
 suffix=nc
 pio_write_args="-f $suffix -w 2 -qtaxis-type=relative"
+# TODO: This script should be splitted into three ones. In the meantime, we
+# assume that if this test is skipped, the two above are skipped as well and we
+# can 'exit 77'.
 . ./pio_write_run
 
 #

tests/pio_cksum_grb2.in

 #!@SHELL@
 @USE_MPI_FALSE@exit 77
-@HAVE_LIBGRIB_API_FALSE@exit 77
 
 pio_write_args="-f grb2 -w 3"
 mpi_task_num=8

tests/pio_write_run.in

@@ -2,7 +2,26 @@
 LOG=${LOG-pio_write.log}
 mpi_task_num="${mpi_task_num-4}"
 suffix="${suffix-grb}"
-test "x${suffix}" != xgrb || test 'x@ENABLE_GRIB@' = xyes || exit 77
+
+case ${suffix} in
+  grb)
+    test 'x@ENABLE_GRIB@' = xyes || exit 77
+    ;;
+  grb2)
+    @HAVE_LIBGRIB_API_FALSE@exit 77
+    ;;
+  nc|nc2)
+    test 'x@ENABLE_NETCDF@' = xyes || exit 77
+    ;;
+  nc4)
+    test 'x@ENABLE_NETCDF@' = xyes || exit 77
+    test 'x@ENABLE_NC4@' = xyes || exit 77
+    ;;
+  *)
+    echo "Unsupported suffix '${suffix}'" >&2
+    exit 1
+    ;;
+esac
 
 @USE_MPI_TRUE@variations="-qno-batch-rma -qcache-redists -qcreate-curvilinear-grid -qpreset-decomposition=true"
 @USE_MPI_FALSE@variations="-qcreate-curvilinear-grid"