Adding dist for aapt2_results

In the previous transition to Android.bp change(aosp/2935114), the
$(call dist-for-goals,aapt2_run_host_unit_tests, ...) was overlooked.
This change added `dist` for `aapt2_results` to fix this issue.

Bug: 322285259
Test: m -j aapt2_run_host_unit_tests dist;
      Then, check ./out/dist/gtest/aapt2_host_unit_tests_result_x86.xml
      and ./out/dist/gtest/aapt2_host_unit_tests_result_x86_64.xml
Change-Id: Ieaa67fef4a47b08fd97f3dc1810f4cd1933f155d