Atomic
This header attempts to replicate some of the types from std::atomic.
If ETL_CPP11_SUPPORTED is defined as 1 in the profile then etl::atomic will be defined in terms of std::atomic.
Otherwise it will be implemented in terms of the built-in support, if available, from the compiler. For example, early
GCC and Arm compilers will use the __sync built-ins.
If a type cannot be handled by the built-ins then the types are wrapped by etl::mutex.
If there is an ETL atomic type available for your platform then ETL_HAS_ATOMIC will be set to 1, otherwise it will be set to
0.