Merge branch 'sb/diff-blobfind-pickaxe'

"diff" family of commands learned "--find-object=<object-id>" option
to limit the findings to changes that involve the named object.

* sb/diff-blobfind-pickaxe:
diff: use HAS_MULTI_BITS instead of counting bits manually
diff: properly error out when combining multiple pickaxe options
diffcore: add a pickaxe option to find a specific blob
diff: introduce DIFF_PICKAXE_KINDS_MASK
diff: migrate diff_flags.pickaxe_ignore_case to a pickaxe_opts bit
diff.h: make pickaxe_opts an unsigned bit field

diff --cc Documentation/diff-options.txt
Simple merge

diff --cc builtin/log.c
Simple merge

diff --cc diff.c
Simple merge

diff --cc diff.h
Simple merge

diff --cc revision.c
Simple merge