Merge branch 'jk/name-decoration-alloc'

The API to allocate the structure to keep track of commit
decoration was cumbersome to use, inviting lazy code to
overallocate memory.

* jk/name-decoration-alloc:
log-tree: use FLEX_ARRAY in name_decoration
log-tree: make name_decoration hash static
log-tree: make add_name_decoration a public function

diff --cc bisect.c
Simple merge

diff --cc commit.h
Simple merge

diff --cc log-tree.c
Simple merge

diff --cc revision.c
Simple merge