cmake: Toolchain abstraction: Introducing macro toolchain_cc_nocommon

The macro is intended to abstract the -fno-common compiler option
which controls the placement of uninitialized global variables. The
macro leaves it up to the toolchain to define the option.

The intent here is to abstract Zephyr's dependence on toolchains,
thus allowing for easier porting to other, perhaps commercial,
toolchains and/or usecases.

No functional change expected.

Signed-off-by: Danny Oerndrup <daor@demant.com>
6 files changed