Fix overapping XMEGA flash memories for dryrun programmer #1315

Job	Run time
macos-x86_64	1m 47s
mingw (mingw32, i686)	2m 50s
mingw (mingw64, x86_64)	3m 27s
linux-x86_64	1m 50s
linux (i386, i686, i686-linux-gnu, i386-linux-gnu)	2m 5s
linux (armhf, armhf, arm-linux-gnueabihf, arm-linux-gnueabihf)	1m 33s
linux (arm64, aarch64, aarch64-linux-gnu, aarch64-linux-gnu)	1m 38s
msvc (x86, Win32)	5m 12s
msvc (x64, x64)	2m 18s
msvc (arm64, ARM64)	2m 19s
	24m 59s

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