Merge branch 'ab/the-index-compatibility'

Merge branch 'ab/the-index-compatibility'

Remove more remaining uses of macros that relies on the_index
singleton instance without explicitly spelling it out.

* ab/the-index-compatibility:
  cocci & cache.h: remove "USE_THE_INDEX_COMPATIBILITY_MACROS"
  cache-tree API: remove redundant update_main_cache_tree()
  cocci & cache-tree.h: migrate "write_cache_as_tree" to "*_index_*"
  cocci & cache.h: apply pending "index_cache_pos" rule
  cocci & cache.h: fully apply "active_nr" part of index-compatibility
  builtin/rm.c: use narrower "USE_THE_INDEX_VARIABLE"