populate-extfs.sh: fix to handle /var/lib/opkg/alternatives/[[ correctly

There was a patch trying to fix this problem by using 'dirname', but it
caused some build failures, thus got reverted.

The problem is that $DIR might be empty and we should first do the check
before trying to use $(dirname $DIR).

[YOCTO #5712]

(From OE-Core rev: 8277c71747758e2ba0815a6f5cd11c9e0c9c90ce)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/e2fsprogs/e2fsprogs-1.42.8/populate-extfs.sh

@@ -23,12 +23,13 @@ DEBUGFS="debugfs"
 	find $SRCDIR | while read FILE; do
                 TGT="${FILE##*/}"
                 DIR="${FILE#$SRCDIR}"
-                DIR="${DIR%$TGT}"
 
 		# Skip the root dir
 		[ ! -z "$DIR" ] || continue
 		[ ! -z "$TGT" ] || continue
 
+                DIR="$(dirname $DIR)"
+
 		if [ "$DIR" != "$CWD" ]; then
 			echo "cd $DIR"
 			CWD="$DIR"