Merge pull request #1474 from MCUdude/megaavr-chiprev #1312

Job	Run time
macos-x86_64	1m 53s
msvc (x86, Win32)	1m 36s
msvc (x64, x64)	1m 55s
msvc (arm64, ARM64)	2m 21s
linux-x86_64	1m 21s
linux (i386, i686, i686-linux-gnu, i386-linux-gnu)	1m 32s
linux (armhf, armhf, arm-linux-gnueabihf, arm-linux-gnueabihf)	1m 38s
linux (arm64, aarch64, aarch64-linux-gnu, aarch64-linux-gnu)	1m 36s
mingw (mingw32, i686)	3m 29s
mingw (mingw64, x86_64)	3m 59s
	21m 20s

Provide feedback