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"