Removed configure flags no longer present in openocd 0.12, and allows
easy configuration of boards. Also removes the two boards that were
enabled before.
with structuredAttrs lists will be bash arrays which cannot be exported
which will be a issue with some patches and some wrappers like cc-wrapper
this makes it clearer that NIX_CFLAGS_COMPILE must be a string as lists
in env cause a eval failure
This issue is fixed in upstream OpenOCD, but there hasn't been a
new release since the fix.
See https://github.com/libusb/libusb/issues/928 for context.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
