21fb95bba6
Fix the newsize argument to arena_run_trim_tail() that arena_dalloc_bin_run() passes. Previously, oldsize-newsize (i.e. the complement) was passed, which could erroneously cause dirty pages to be returned to the clean available runs tree. Prior to the CHUNK_MAP_ZEROED --> CHUNK_MAP_UNZEROED conversion, this bug merely caused dirty pages to be unaccounted for (and therefore never get purged), but with CHUNK_MAP_UNZEROED, this could cause dirty pages to be treated as zeroed (i.e. memory corruption).