sha1_file: use the correct type (ssize_t, not size_t) for read-style function
sha1_file: use the correct type (ssize_t, not size_t) for read-style function

Using an unsigned type, we would fail to detect a read error and then
proceed to try to write (size_t)-1 bytes.

Signed-off-by: Jim Meyering <15b0b14300fba1cff8c70eb2a5c1720ef2a4c654@redhat.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git