read-cache.c: use xcalloc() not calloc()
read-cache.c: use xcalloc() not calloc()

Elsewhere we use xcalloc(); we should consistently do so.

Signed-off-by: Yakov Lerner <cde89003d6b4c0cb318d7d640a10052a2b179ff3@gmail.com>
Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

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