Improve cancellation test for async DNS API

After having a lock between callback and cancellationsignal,
errno with EBADF should not happen.

Bug: 129317069
Test: atest DnsResolverTest
Change-Id: I08e800b078d40345eb3f46da1323db251c8dcd47
1 file changed
tree: d72550accf16962ff43201efb7cff43b98392b3b
  1. tests/