makefile: optimize compile flags

Signed-off-by: Dan Trifan <jimsth@gmail.com>
arch:arm:configs: defconfig update for new wifi drivers

Signed-off-by: Dan Trifan <jimsth@gmail.com>
build.sh: change zips name to *_exp_wifi, test gcc 4.7 from google

Signed-off-by: Dan Trifan <jimsth@gmail.com>