fasl-write problem with records because of struct-type-field-names

Will fix. There are also a few things the fasl-read procedure cannot read yet (some number types I think). Will fix those too.

Fixed in rev 1405.

> (let ()
    (define-record-type my-thing (fields x))
    (define t0 (make-my-thing 123))
    (let-values ([(bvop bvop-getter) (open-bytevector-output-port)])
      (fasl-write t0 bvop)
      (let ([bv (bvop-getter)])
        (for-each
          (lambda (n) (printf "~x~x" (div n 16) (mod n 16)))
          (bytevector->u8-list bv))
        (newline)
        (let ([obj (fasl-read (open-bytevector-input-port bv))])
          (list t0 obj (and (my-thing? obj) (my-thing-x obj)))))))
2340494B30317B01000000574D73080000006D792D7468696E67464773020000006730731000000046246A392F35242F4C5877324A47395A46464904000000464D73010000007849EC010000
(#[my-thing 123] #[my-thing 123] 123)

That output was too ugly. Here's a fix.

> (let ()
    (import (hexdump))
    ;;; from https://code.launchpad.net/~aghuloum/ikarus-libraries/r6rs-hexdump
    (define-record-type my-thing (fields x))
    (define t0 (make-my-thing 123))
    (let-values ([(bvop bvop-getter) (open-bytevector-output-port)])
      (fasl-write t0 bvop)
      (let ([bv (bvop-getter)])
        (hexdump bv)
        (let ([obj (fasl-read (open-bytevector-input-port bv))])
          (list t0 obj (and (my-thing? obj) (my-thing-x obj)))))))
0x00000000 23 40 49 4B 30 31 7B 01 00 00 00 57 4D 73 08 00 | #@IK01{....WMs.. |
0x00000010 00 00 6D 79 2D 74 68 69 6E 67 46 47 73 02 00 00 | ..my-thingFGs... |
0x00000020 00 67 30 73 10 00 00 00 6B 55 44 78 39 30 55 35 | .g0s....kUDx90U5 |
0x00000030 59 57 3E 76 6B 71 3D 58 46 46 49 04 00 00 00 46 | YW>vkq=XFFI....F |
0x00000040 4D 73 01 00 00 00 78 49 EC 01 00 00 | Ms....xI.... |
(#[my-thing 123] #[my-thing 123] 123)