This commit fixes configuration problems when trying to use i2c pins that need to be remapped.
All B8 and B9 pins for STM32F1 need to be remapped, so a check is done if the remappable pins are selected.

The file always exist so no need to do '-include'.

Replaced using:

    sed -i 's|-\(include $(RIOTCPU)/.*/Makefile.features\)|\1|' \
        $(git grep -l  '$(RIOTCPU)/.*/Makefile.features' boards)