Merge branch 'jk/cat-file-buffered-batch-all'

"git cat-file --batch-all" has been sped up, by taking advantage
of the fact that it does not have to read a list of objects, in two
ways.

* jk/cat-file-buffered-batch-all:
cat-file: default to --buffer when --batch-all-objects is used
cat-file: avoid noop calls to sha1_object_info_extended

diff --cc builtin/cat-file.c
Simple merge