and define it to true for __aarch64__ and Win Arm64 + Visual Studio.
Microsoft's compiler (cl.exe) does not define __aarch64__, but relies on
_M_ARM64 & _M_ARM64EC
Bug: b/277254922
Change-Id: I20e4fa07a4031599db69e3d7ba9050345315ef51
this moves the function outside the WEBP_USE_INTRINSICS check.
there's no alternative version and it's ~54% faster at the
function level and mildly faster overall
Change-Id: Ibc648e9ee35021d48901e05aa596aa01067796a2
generates a stub function when the specific architecture is not enabled,
exposing a symbol in the module, avoiding a compiler warning
Change-Id: Ia9336e57466a9b5241b85c1c95838e91c9283147