glocalfile: Handle smb2 filesystem type

`G_FILE_ATTRIBUTE_FILESYSTEM_TYPE` is not set for CIFS mounts with
`vers=2.0` option, or newer. Add `smb2` to the list of known filesystems.
It is also reported by `stat -f`:
https://github.com/coreutils/coreutils/blob/master/src/stat.c

gio/glocalfile.c

@@ -690,6 +690,8 @@ get_fs_type (long f_type)
       return "smackfs";
     case 0x517B:
       return "smb";
+    case 0xfe534d42:
+      return "smb2";
     case 0x534F434B:
       return "sockfs";
     case 0x73717368: