FS-353: look for ldns pkg-config for homebrew, you will need to update your…

FS-353: look for ldns pkg-config for homebrew, you will need to update your homebrew ldns package if you installed it prior to this commit, they just fixed the pkg-config file being installed

configure.ac

@@ -1118,6 +1118,7 @@ case $host in
    *-darwin*)
         path_push_unique PKG_CONFIG_PATH /usr/local/opt/curl/lib/pkgconfig
         path_push_unique PKG_CONFIG_PATH /usr/local/opt/sqlite/lib/pkgconfig/
+        path_push_unique PKG_CONFIG_PATH /usr/local/opt/ldns/lib/pkgconfig/
        ;;
 esac