directory: converted typedef Directory to struct directory

The struct can be forward-declared by other headers, which relaxes the
header dependencies.

src/dbUtils.c

@@ -46,8 +46,8 @@ typedef struct _SearchStats {
 	unsigned long playTime;
 } SearchStats;
 
-static int countSongsInDirectory(Directory * directory,
-				 void *data)
+static int
+countSongsInDirectory(struct directory *directory, void *data)
 {
 	int *count = (int *)data;
 
@@ -56,7 +56,8 @@ static int countSongsInDirectory(Directory * directory,
 	return 0;
 }
 
-static int printDirectoryInDirectory(Directory * directory, void *data)
+static int
+printDirectoryInDirectory(struct directory *directory, void *data)
 {
 	struct client *client = data;
 	if (directory->path) {
@@ -356,15 +357,16 @@ int listAllUniqueTags(struct client *client, int type, int numConditionals,
 	return ret;
 }
 
-static int sumSavedFilenameMemoryInDirectory(Directory * dir, void *data)
+static int
+sumSavedFilenameMemoryInDirectory(struct directory *dir, void *data)
 {
 	int *sum = data;
 
 	if (!dir->path)
 		return 0;
 
-	*sum += (strlen(getDirectoryPath(dir)) + 1 - sizeof(Directory *)) *
-	    dir->songs.nr;
+	*sum += (strlen(getDirectoryPath(dir)) + 1
+		 - sizeof(struct directory *)) * dir->songs.nr;
 
 	return 0;
 }