DnsResolver: refix -Wreorder-init-list

Either this snuck in because I haven't completed the platform compiler
upgrade yet, or is only visible via checkbuild.

Test: m checkbuild
Bug: 139945549
Change-Id: Ida791b16fdca64ebef528df45a07cb6ef1af6636
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>