hostapd: fix static build failure

libnl-3 uses threads and this isn't accounted for in hostapd (or
libnl-3*.pc files for that matter - hostapd doesn't use pkg-config
anyway).
Since linking order matters for static scenarios also throw in -lnl-3
into LIBS first since it gets appended to in hostapd makefiles to add
libnl-3.

Fixes:
http://autobuild.buildroot.net/results/d4a/d4a9f44effeb08eda6c4b32764274ae81d185d5e/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>