vchoi_fork

[svn-r2693] Purpose:
    Bug fix (bug #446)
Description:
    H5Tget_offset return type was size_t and the error return value was 0, but
    0 is also a valid successful return value.
Solution:
    Changed the return type to int and the error return value to -1
Platforms tested:
    FreeBSD 4.1.1 (hawkwind)