resolv_gold_test: use compile_multilib:"both" with "32"/"64" suffixes

Needed for running tests on atest and mts coverage (32bit only).

Bug: 237986214
Test: atest resolv_gold_test
Test: m mts && mts-tradefed run mts-dnsresolver
Change-Id: I17eca0a37a8f034539c3d630a837140d64ed12f1