dfu-util warns when flashing a .bin file that has no "dfu suffix". Now
we use dfu-suffix, if available, to add the dfu suffix; otherwise keep
the original dfu-util command line as a reflash target; fixes#56 GH.
Also add .bin files as BYPRODUCTS so that 'make clean' picks them up
too.
We need to specify -Wno-deprecated at the top level, and not just when
building stm32_HAL because any regular source file that includes in stm32f0xx_hal.h also pulls in those cmsis headers that trigger the deprecation warning.