package/c-ares: fix install

c-ares 1.17.0 removed install of ares_dns.h which will result in build
failures with libeXosip and resiprocate

Fixes:
 - http://autobuild.buildroot.org/results/51573434303118fd92f32819e038971edee8bc28
 - http://autobuild.buildroot.org/results/cbf158f0c037d44ef293a8804d18c84e3b731059

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2 files changed