btrfs-progs: test: fix name generation not to contain trailing spaces

First patch causes test-convert fails.  This is because
generate_dataset() creates a name containing trailing spaces for
"slow_symlink" type, and cause getfacl error in convert_test_perm().
(This is not noticed since original run_check_stdout() throws away the
error.)

Fix this by use space for delimiter for cut.

Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

tests/common

@@ -509,7 +509,7 @@ generate_dataset() {
 			;;
 
 		slow_symlink)
-			long_filename=`date +%s | sha256sum | cut -f1 -d'-'`
+			long_filename=`date +%s | sha256sum | cut -f1 -d ' '`
 			run_check $SUDO_HELPER touch "$dirpath/$long_filename"
 			for num in $(seq 1 "$DATASET_SIZE"); do
 				run_check $SUDO_HELPER ln -s "$dirpath/$long_filename" "$dirpath/slow_slink.$num"