toolchain: xcc: Builtin overflow functions return boolean
toolchain: xcc: Builtin overflow functions return boolean

The builtin_*_overflow functions when available return a
boolean. Change internal definitions to return same type.

Signed-off-by: Flavio Ceolin <979b9165500b0741b9d0500e2efd74fc1547bff7@intel.com>

ldts/zephyr,Vudentz/zephyr,punitvara/zephyr,galak/zephyr,explora26/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,explora26/zephyr,nashif/zephyr,nashif/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,finikorg/zephyr,punitvara/zephyr,Vudentz/zephyr,punitvara/zephyr,punitvara/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,explora26/zephyr,ldts/zephyr,ldts/zephyr,nashif/zephyr,galak/zephyr,explora26/zephyr,punitvara/zephyr,nashif/zephyr