Without this, linking against libring fails with missing symbols from
libring-core. Soong does not propagate static_libs across targets, and
apparently this behavior is WAI.

Bug: 193446464
Bug: 155855709
Test: Remove libring-core from doh_ffi_test and run "m doh_ffi_test"

Change-Id: I26c8628fe6485e5859e8ce8c1d1ea0866d257184
Merged-In: I3068448cf7b58fcad775342dc6fa0db36f9c664e
(cherry picked from commit 16c1cfd5)