MSVC's arm64 cl.exe rejects GCC inline asm (asm volatile mrs/msr FPCR),
which broke the Windows arm64 build (C2059 syntax error: 'volatile',
cascading to 100+ errors per TU). Read/write FPCR via the system-register
intrinsics _ReadStatusReg/_WriteStatusReg(ARM64_FPCR) under
(_MSC_VER && !__clang__); clang/clang-cl keep the inline asm. <intrin.h>
(which declares these) is already included by VectorIntrin.h under _MSC_VER.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>