mdnsd: add query / fetch methods, fix some bugs

Signed-off-by: Steven Barth <steven@midlink.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43169 3c298f89-4303-0410-b956-a3cf2f4a3e73
polarssl: update to 1.3.9

Signed-off-by: Steven Barth <steven@midlink.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43170 3c298f89-4303-0410-b956-a3cf2f4a3e73