This change allows a port to provide its own implementation of: * core_util_critical_section_enter * core_util_critical_section_exit Some system like the NRF series require specific behavior for the critical section and now can override it properly.
"#3731-D: intrinsic is deprecated" compiler warnings should only be suppressed on the ARM toolchain.
Suppressed "#3731-D: intrinsic is deprecated" compiler warnings in critical API.