blkid: optional support for TYPE="fstype"

Adapted from patch created by T4ndeta <t4ndeta@gmail.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

include/volume_id.h

@@ -28,3 +28,4 @@ void display_uuid_cache(void);
  *    *fsname is replaced if device with such UUID or LABEL is found
  */
 int resolve_mount_spec(char **fsname);
+int add_to_uuid_cache(const char *device);