When building a release, move existing signals.cpp out of the way.
When building a release, move existing signals.cpp out of the way.

Fixed #249.

openxc/vi-firmware,mgiannikouris/vi-firmware,ene-ilies/vi-firmware,openxc/vi-firmware,openxc/vi-firmware,openxc/vi-firmware,ene-ilies/vi-firmware,mgiannikouris/vi-firmware,ene-ilies/vi-firmware,ene-ilies/vi-firmware,mgiannikouris/vi-firmware,mgiannikouris/vi-firmware