emulation on host: Make non essential ARDUINO LIBS optional. (#5771)
emulation on host: Make non essential ARDUINO LIBS optional. (#5771)

This patch splits ARDUINO_LIBS into two variables. The second variable is called OPT_ARDUINO_LIBS and can be overridden by the caller as it uses the ?= assignment operator. Additionally it unifies and simplifies collecting the files in common/ by using the addprefix macro. All changes should be 100% backwards compatible.
Lan-Hekary/Arduino,Lan-Hekary/Arduino,esp8266/Arduino,esp8266/Arduino,Lan-Hekary/Arduino,sticilface/Arduino,sticilface/Arduino,sticilface/Arduino,esp8266/Arduino,sticilface/Arduino,esp8266/Arduino,Lan-Hekary/Arduino,sticilface/Arduino,esp8266/Arduino,Lan-Hekary/Arduino