vchoi_fork

[svn-r1128] Changes for T3E port.

H5Flow.c:
    Document previous changes (same changes committed by Robb first.)

H5Fprivate.h:
    Change DECODE macros to do sign extension.
    (Sign extension can be skipped if machines use the exact sizes.)

H5Sall.c:
    Fixed a typo in return value.

H5private.h:
    Fixed a typo and also changed the strategy of the int16_t and
    uint16_t typedef.  Now will use short as long as it is at least
    2 bytes big.