Make unpack_trees() do separate source and destination indexes

Ok, this goes on top of the five-commit series yesterday. The first two patches are pure fixes and cleanups, the third one does a fairly mechanical thing to get rid of implied usage of "the_index", and the last one actually splits up the source and destination index handling.

Linus Torvalds (4):
Fix tree-walking compare_entry() in the presense of --prefix Add 'const' where appropriate to index handling functions Make 'unpack_trees()' take the index to work on as an argument Make 'unpack_trees()' have a separate source and destination index

The nice thing to see is how this clearly removes more lines than it adds, and the code is a bit more readable too, I think.

 builtin-checkout.c        |    9 +++
 builtin-commit.c          |    2 +
 builtin-merge-recursive.c |    2 +
 builtin-read-tree.c       |   23 +------
 cache.h                   |   10 ++--
 diff-lib.c                |   47 ++-----------
 hash.c                    |    6 +-
 hash.h                    |    4 +-
 read-cache.c              |   12 ++--
 tree-walk.c               |    3 +
 unpack-trees.c            |  158 ++++++++++++++++++++++-----------------------
 unpack-trees.h            |   15 +++--
 12 files changed, 128 insertions(+), 163 deletions(-)