PATCH: fastjar doesn't skip zip's extra fields correctly

[Tom Tromey]

>>>>> "DU" == Daiki Ueno <ueno@unixuser.org> writes:

DU> I found that some zip files couldn't be extracted with fastjar.  More
DU> precisely, when such a zip file is present as an argument, zip's extra
DU> fields are not properly skipped because jartool.c:extract_jar does
DU> lseek(2) although in case pushback buffer is not empty.

Thanks.  This looks good.  I'm checking it on in on the trunk and the
3.3 branch.

Tom