[PATCH 0/1] MR1219: ntdll: Fix building on Mojave / Xcode 11.3.1.

[Stefan Dösinger (＠stefan)]

_STRUCT_X86_THREAD_FULL_STATE64 exists, but _STRUCT_MCONTEXT64_FULL and
_STRUCT_MCONTEXT_AVX64_FULL do not.