broadcom-wl: fix build with musl

This fixes some build problems with musl. The binary only program 
nas.exe wants to link against __assert, which is copied from uClibc.

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


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@46021 3c298f89-4303-0410-b956-a3cf2f4a3e73