Redo "git name-rev" to avoid recursive calls.
* sg/name-rev-wo-recursion:
name-rev: cleanup name_ref()
name-rev: eliminate recursion in name_rev()
name-rev: use 'name->tip_name' instead of 'tip_name'
name-rev: drop name_rev()'s 'generation' and 'distance' parameters
name-rev: restructure creating/updating 'struct rev_name' instances
name-rev: restructure parsing commits and applying date cutoff
name-rev: pull out deref handling from the recursion
name-rev: extract creating/updating a 'struct name_rev' into a helper
t6120: add a test to cover inner conditions in 'git name-rev's name_rev()
name-rev: use sizeof(*ptr) instead of sizeof(type) in allocation
name-rev: avoid unnecessary cast in name_ref()
name-rev: use strbuf_strip_suffix() in get_rev_name()
t6120-describe: modernize the 'check_describe' helper
t6120-describe: correct test repo history graph in comment
f3c520e17f