Add entry for riscv64gc-unknown-netbsd (to support NetBSD/riscv64). #370

Job	Run time
Rustfmt	6s
Test (x86_64-unknown-linux-gnu, stable, ubuntu-latest)	6m 27s
Test (x86_64-unknown-linux-gnu, beta, ubuntu-latest)	6m 31s
Test (x86_64-unknown-linux-gnu, nightly, ubuntu-latest)	7m 43s
Test (x86_64-apple-darwin, stable, macos-latest)	6m 35s
Test (aarch64-apple-darwin, nightly, macos-latest)	6m 1s
Test (i686-unknown-linux-gnu, stable, ubuntu-latest)	3m 36s
Test (arm-unknown-linux-gnueabi, stable, ubuntu-latest)	3m 53s
Test (aarch64-unknown-linux-gnu, stable, ubuntu-latest)	4m 10s
Test (x86_64-unknown-linux-musl, stable, ubuntu-latest)	3m 31s
Test (x86_64-pc-windows-gnu, stable, ubuntu-latest)	5m 5s
Test (wasm32-wasi, stable, ubuntu-latest)	6m 2s
Test (i686-pc-windows-msvc, stable-i686-msvc, windows-2019)	17m 45s
Test (i686-pc-windows-msvc, stable-i686-msvc, windows-2019, yes)	17m 28s
Test (x86_64-pc-windows-msvc, stable-x86_64-msvc, windows-latest)	20m 32s
Test (x86_64-pc-windows-msvc, stable-x86_64-msvc, windows-latest, yes)	26m 15s
Test (x86_64-pc-windows-msvc, stable-x86_64-msvc, windows-latest, installed)	15m 58s
	2h 37m 38s

Provide feedback