When building the virtual boards, we want to have the base core as
`keyboardio:arduino`, instead of `arduino:arduino`, because we provide the base
ourselves. To this end, instead of symlinking `avr/boards.txt` and
`virtual/boards.txt`, generate the latter from the former.
Once we have other architectures, such as SAMD, we can concat all the boards.txt
files and do the same `base.core` replacements.
This is a pre-requisite for keyboardio/Kaleidoscope#851.
Signed-off-by: Gergely Nagy <algernon@keyboard.io>
Apparently, having the hardware directory within the current directory does not
work all that well now, and Arduino fails to find it. Moving it one level
higher, outside of the cloned sources, and all is well.
This is the major part of the fix for #27.
Signed-off-by: Gergely Nagy <algernon@keyboard.io>
