Remove spl/zfs modules as part of cleanup

The idea behind the '-c' flag is to cleanup everything from a
previous test run which might cause the test script to fail.
This should also include removing the previously loaded module.
This makes it a little easier to run 'zconfig.sh -c', however
remember this is a test script and it will take all of your
other zpools offline for the purposes of the test.  This notion
has also been extended to the default 'make check' behavior.

scripts/Makefile.am

@@ -36,6 +36,7 @@ clean:
 	done
 
 check:
+	@$(ZFS) -u
 	@echo
 	@echo -n "===================================="
 	@echo -n " ZTEST "

scripts/Makefile.in

@@ -732,6 +732,7 @@ clean:
 	done
 
 check:
+	@$(ZFS) -u
 	@echo
 	@echo -n "===================================="
 	@echo -n " ZTEST "

scripts/zconfig.sh

@@ -60,6 +60,7 @@ fi
 
 # Perform pre-cleanup is requested
 if [ ${CLEANUP} ]; then
+	${ZFS_SH} -u
 	cleanup_md_devices
 	cleanup_loop_devices
 	rm -f /tmp/zpool.cache.*

scripts/zfault.sh

@@ -88,6 +88,7 @@ fi
 
 # Perform pre-cleanup is requested
 if [ ${CLEANUP} ]; then
+	${ZFS_SH} -u
 	cleanup_md_devices
 	cleanup_loop_devices
 	rm -f /tmp/zpool.cache.*