Use correct ABI on NetBSD/riscv64, and add target entry for same. #717

Job	Run time
Rustfmt	11s
MSRV (ubuntu-latest)	55s
MSRV (windows-latest)	1m 22s
Test CUDA support	1m 2s
Test (stable)	43s
Test (beta)	41s
Test (nightly)	42s
Test (linux32)	2m 0s
Test (macos)	1m 17s
Test (aarch64-ios)	1m 18s
Test (win32)	1m 48s
Test (win64)	2m 59s
Test (mingw32)	1m 41s
Test (mingw64)	1m 48s
Test (windows-2019)	2m 21s
Test (windows-aarch64, windows-latest, stable, aarch64-pc-windows-msvc, --no-run)	7m 7s
	27m 55s

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