Various parts of upload-pack has been updated to bound the resource
consumption relative to the size of the repository to protect from
abusive clients.
* jk/upload-pack-bounded-resources:
upload-pack: free tree buffers after parsing
upload-pack: use PARSE_OBJECT_SKIP_HASH_CHECK in more places
upload-pack: always turn off save_commit_buffer
upload-pack: disallow object-info capability by default
upload-pack: accept only a single packfile-uri line
upload-pack: use a strmap for want-ref lines
upload-pack: use oidset for deepen_not list
upload-pack: switch deepen-not list to an oid_array
upload-pack: drop separate v2 "haves" array