Merge branch 'js/fsck-tag-validation'

Teach "git fsck" to inspect the contents of annotated tag objects.

* js/fsck-tag-validation:
Make sure that index-pack --strict checks tag objects
Add regression tests for stricter tag fsck'ing
fsck: check tag objects' headers
Make sure fsck_commit_buffer() does not run out of the buffer
fsck_object(): allow passing object data separately from the object itself
Refactor type_from_string() to allow continuing after detecting an error

diff --cc builtin/fsck.c
Simple merge

diff --cc builtin/index-pack.c
Simple merge

diff --cc t/t1450-fsck.sh
Simple merge