package/dnsmasq: Fix link error with gettext

-lintl needs to be added at the end of the link command, Makefile
has variable LIBS for this purpose, so use it instead of LDFLAGS.

Fixes
http://autobuild.buildroot.net/results/276/276581f6dbbe330799c3a7eaa26b453e38a22907/



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>