Ignore -Wvolatile warnings from STM32 HAL

CMakeLists.txt

@@ -11,7 +11,7 @@ SET(CMAKE_SYSTEM_NAME Generic)
 set(COMMON_FLAGS "-mcpu=cortex-m3 -mthumb -Wall -fdata-sections -ffunction-sections")
 set(CMAKE_ASM_FLAGS "${COMMON_FLAGS} -x assembler-with-cpp")
 set(CMAKE_C_FLAGS "${COMMON_FLAGS}")
-set(CMAKE_CXX_FLAGS "${COMMON_FLAGS}")
+set(CMAKE_CXX_FLAGS "${COMMON_FLAGS} -Wno-volatile")
 
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_CXX_STANDARD 20)