build: move compiler warning flags to separate autoconf variable
build: move compiler warning flags to separate autoconf variable

thom311/libnl,dsahern/libnl,tklauser/libnl,greearb/libnl-ct,dsahern/libnl,dsahern/libnl,dsahern/libnl,tklauser/libnl,tklauser/libnl,tklauser/libnl,thom311/libnl,greearb/libnl-ct,greearb/libnl-ct,thom311/libnl