* asan.h (ASAN_STACK_MAGIC_PARTIAL): Remove.
* asan.c (ASAN_STACK_MAGIC_PARTIAL): Replace with
ASAN_STACK_MAGIC_MIDDLE.
(asan_global_struct): Increase the size of fields.
(asan_add_global): Add new field constructor.
* sanitizer.def (__asan_version_mismatch_check_v6): Replace with
__asan_version_mismatch_check_v8.