The build process does not leak the user space cflags into the kernel
build process any more, this allows to activate MIPS16 builds.
This was fixed with some update of ifxos.

This decreases size of the  libifxos.a and the ltq-vdsl-app
old:
78320 libifxos.a
44383 ltq-vdsl-app_4.17.18.6-2_mips_24kc.ipk

new:
66852 libifxos.a
43506 ltq-vdsl-app_4.17.18.6-2_mips_24kc.ipk

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>