Merge branch 'il/maint-xmallocz'

* il/maint-xmallocz:
  Fix integer overflow in unpack_compressed_entry()
  Fix integer overflow in unpack_sha1_rest()
  Fix integer overflow in patch_delta()
  Add xmallocz()

diff --cc git-compat-util.h
Simple merge

diff --cc sha1_file.c
Simple merge