Compile warning in native c source files

[thortex]

gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -Inative/ -I/usr/include/python2.7 -c native/bridge.c -o build/temp.linux-armv6l-2.7/native/bridge.o native/bridge.c: In function ‘py_set_pullupdn’: native/bridge.c:184:6: warning: unused variable ‘function’ [-Wunused-variable] gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -Inative/ -I/usr/include/python2.7 -c native/gpio.c -o build/temp.linux-armv6l-2.7/native/gpio.o gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -Inative/ -I/usr/include/python2.7 -c native/cpuinfo.c -o build/temp.linux-armv6l-2.7/native/cpuinfo.o gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -Inative/ -I/usr/include/python2.7 -c native/pwm.c -o build/temp.linux-armv6l-2.7/native/pwm.o native/pwm.c: In function ‘wip_pwm_cleanup’: native/pwm.c:284:5: warning: passing argument 1 of ‘free’ discards ‘volatile’ qualifier from pointer target type [enabled by default] /usr/include/stdlib.h:483:13: note: expected ‘void ’ but argument is of type ‘volatile uint8_t ’ native/pwm.c:289:5: warning: passing argument 1 of ‘free’ discards ‘volatile’ qualifier from pointer target type [enabled by default] /usr/include/stdlib.h:483:13: note: expected ‘void ’ but argument is of type ‘volatile uint8_t ’ gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-z,relro build/temp.linux-armv6l-2.7/native/bridge.o build/temp.linux-armv6l-2.7/native/gpio.o build/temp.linux-armv6l-2.7/native/cpuinfo.o build/temp.linux-armv6l-2.7/native/pwm.o -o build/lib.linux-armv6l-2.7/_webiopi/GPIO.so