Add support for ARM64EC when building with MSVC #922

Job	Run time
Test (stable)	26s
Test (beta)	24s
Test CUDA support	38s
Test (nightly)	25s
MSRV (ubuntu-latest)	23s
Test (linux32)	47s
Test aarch64-apple-tvos	2m 21s
MSRV (windows-latest)	43s
Test (macos)	1m 41s
Test (aarch64-ios)	46s
Test (win32)	1m 16s
Rustfmt	14s
Test (win64)	1m 37s
Test (mingw32)	1m 16s
Test (mingw64)	1m 14s
Test (windows-2019)	2m 29s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	2m 5s
	18m 45s

Provide feedback