When flashing the ESP8266 with the flash tool it is possible to connect
RTS to the reset line and DTR to GPIO0 to automatically reboot the
device into flash mode and then reboot the device again into normal
mode.
pyterm leaves these two signals unset unless we specify a --set-rts=0 or
1, and the value of these lines would depend on the UART driver.
This patch explicitly sets RTS and DTR to 0 (high level) in the
Makefile.include config so `make term` releases the reset line,
otherwise the device may be left in reset mode after pyterm starts.
cpu/$(CPU)/Makefile.features and cpu/$(CPU)/Makefile.dep are
automatically included
Part of moving CPU/CPU_MODEL definition to Makefile.features to have it
available before Makefile.include.
* CPU files should already have 'CPU' defined by the board.
* Do not conditionally define CPU as it is not needed.
This is part of cleanup prior to moving the CPU/CPU_MODEL to
Makefile.features.
RESET and RESET_FLAGS are evaluated by the main Makefile.include or by file
included by it. Their value does not need to be exported.
This will also prevent evaluating 'PORT' for RESET_FLAGS when not needed.
Testing
-------
`git diff --word-diff` only reports `export` being removed.
`git show --stat` reports `24 insertions(+), 24 deletions(-)`
Which is the same amount as lines that where matching
`export[[:blank::]]\+VARIABLE`.
