* configure.ac: Define HAS_PPC_THREAD_STATE_R0,
HAS_PPC_THREAD_STATE___R0, HAS_PPC_THREAD_STATE64_R0,
HAS_PPC_THREAD_STATE64___R0, HAS_I386_THREAD_STATE_EAX,
HAS_I386_THREAD_STATE___EAX.
* configure: Regenerate.
* include/gc_config.h.in: Regenerate.
* darwin_stop_world.c (PPC_RED_ZONE_SIZE): Use standard Darwin
macro names to determine value.
(THREAD_STATE): New.
(THREAD_FLD): New.
(GC_push_all_stacks): Use THREAD_STATE and THREAD_FLD in both versions.