Well, in this case the conversion will even be successful as avk noted. Allowing hex numbers in C notation in Pascal is a bit surprising (instead of preceeding '$'), and allowing to start them with "x" instead of "0x" even more (at least to me as a non-C programmer). Is "xd" a valid C hex number? (or must it be "0xd"?) If not we have a bug here.
[EDIT]
Delphi accepts 'xd' as valid integer, too, and returns 13 like FPC.