Add support for ARM64EC when building with MSVC #921

Job	Run time
MSRV (ubuntu-latest)	21s
MSRV (windows-latest)	49s
Rustfmt	10s
Test CUDA support	23s
Test aarch64-apple-tvos	3m 19s
Test (stable)	26s
Test (beta)	25s
Test (nightly)	26s
Test (linux32)	42s
Test (macos)	47s
Test (aarch64-ios)	56s
Test (win32)	1m 1s
Test (win64)	58s
Test (mingw32)	1m 5s
Test (mingw64)	1m 1s
Test (windows-2019)	1m 3s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	59s
	14m 51s

Provide feedback