Write a data descriptor containing the CRC of the entry and its sizes
after streaming it out. For simplicity, do that only if we're storing
files (option -0) for now.
t5000 verifies output. t1050 makes sure the command always respects
core.bigfilethreshold
Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>