update C++ standard (c++11 -> c++14)

- temporarily disable snapdragon builds until toolchain is updated

src/drivers/uavcan/uavcan_drivers/kinetis/driver/CMakeLists.txt

@@ -2,6 +2,7 @@ include_directories(
     ./include
     )
 
+add_compile_options(-Wno-unused-variable)
 add_library(uavcan_kinetis_driver STATIC
     ./src/uc_kinetis_flexcan.cpp
     ./src/uc_kinetis_clock.cpp

src/drivers/uavcan/uavcan_drivers/kinetis/driver/src/uc_kinetis_flexcan.cpp

@@ -693,7 +693,7 @@ void CanIface::handleRxInterrupt(uavcan::uint32_t rx_iflags, uavcan::uint64_t ut
 		frame.data[7] = rf.data.b7;
 
 		volatile uavcan::uint32_t idhit = can_->RXFIR;
-		UNUSED(idhit);
+
 		(void)can_->TIMER;
 		can_->IFLAG1 = flexcan::CAN_FIFO_NE;