arena_types.h + arena_structs.h + arena_externs.h merged into arena.h,
keeping the three logical sections (TYPES / STRUCTS / EXTERNS) with
explicit dividers. arena_inlines_a.h and arena_inlines_b.h stay
separate; arena_inlines_b.h now carries a comment explaining why
merging the two would reintroduce a real #include cycle through
tcache_inlines.h -> arena_choose (the asymmetric cycle-breaker).
arena_decay_constants.h (new): minimal header for
ARENA_DECAY_NTICKS_PER_UPDATE.
Both components had a four-way split (_types, _structs, _externs,
_inlines) that predates explicit per-file includes. With the edata
<-> prof_types coupling broken in the prior commit, merging _types +
_structs + _externs no longer risks an include cycle.
- prof.h replaces prof_types.h + prof_structs.h + prof_externs.h.
- tcache.h replaces tcache_types.h + tcache_structs.h + tcache_externs.h.
prof_inlines.h and tcache_inlines.h stay separate: prof_inlines.h
sits at the bottom of the dependency layering, and tcache_inlines.h's
include of arena_externs.h is the asymmetric cycle-breaker that keeps
the arena <-> tcache symbol cycle from becoming an include cycle.
Fold historical *_types/_structs/_externs/_inlines splits where the
layering is no longer load-bearing.
- large_externs.h -> large.h: rename; it was a single-purpose
function-prototype file.
- background_thread_structs.h + background_thread_externs.h ->
background_thread.h: merge. background_thread_inlines.h stays
separate because it depends on arena_inlines_a.h.
- bin_types.h -> bin.h: BIN_SHARDS_MAX / N_BIN_SHARDS_DEFAULT join the
bin_t struct and the bin_dalloc_locked_info_t type. bin_inlines.h
stays separate so TUs that only need the bin_t type don't pull in
the tcache-flush inline closure. The two bin_stats_* helpers move
from bin.h into bin_inlines.h so all bin inlines live together.
- tsd_binshards.h (new): houses tsd_binshards_t and its zero
initializer. Lets tsd_internals.h pull it in for X-macro expansion
without dragging mutex.h -- mutex.h depends on TSD machinery, which
would form a cycle through bin.h.
jemalloc_internal_includes.h drops the references to the deleted/
merged headers.