Fix Windows ARM64/ARM64EC NEON detection and MSVC compatibility

[navvyswethgraphics]

Summary & Changes

This PR enables clean builds of Chipmunk’s "cpHastySpace.c" on Windows ARM64 and ARM64EC toolchains by fixing NEON guards, avoiding MSVC‑incompatible NEON compound literals, and architecture/compiler checks.

Replaced non‑portable ARM64 checks with aarch64 macros.
Updated vmake() to avoid MSVC‑unsupported NEON compound literals.
Scoped vrev() fallback to compiler (MSVC vs non‑MSVC), avoiding "__builtin_shufflevector" where unsupported.
Replaced {} vector initialization with vdup_n(0.0) for portability.
Applied the corrected NEON guard consistently in the solver path.

Build & test

• Environment: Windows 11 on ARM64, MSVC (Platform toolset: VS 2022(v143)
• Successfully ran "chipmunk_demos" as a smoke test.

Notes

• No behavioral changes on x86/x64.
• NEON code paths are guarded with "_M_ARM64"