a lot of configuration/definition is shared between platforms that build
using gcc.
This start to regroup things that are common into 2 files
com_GCC_defs.mk and com_GCC_class.mk
this can be expanded to be, more generically com_$(COM)_defs/class

The reson for 2 files is that some step need to modfify common definitions
based on the platform and some common definitions need platform defined
value.
with these 2 files we can do a
platform - compiler - platform - compiler - platfrom
sandwich that should cover every scenario.