Fix resolv_{unit,gold}_test linking problem caused by Rust libs

The new linked Rust libs in DnsReoslver caused the
resolv_{unit,gold}_test executive problems due to missing libunwind
symbol.
Add libunwind into whole_static_libs list to fix the problem.

Test: manually run resolv_{unit,gold}_test in Android 10 device
Bug: 193850030
Change-Id: I9013085a20f8fd8bfb8b6f7e9fb7e33a327b98fe
diff --git a/Android.bp b/Android.bp
index 5e2f35c..eead5ab 100644
--- a/Android.bp
+++ b/Android.bp
@@ -397,7 +397,8 @@
         "liburl",
     ],
     prefer_rlib: true,
-
+    // For unit tests to run on the Android 10 platform, libunwind must be statically linked..
+    whole_static_libs: ["libunwind"],
     apex_available: [
         "//apex_available:platform",  // Needed by doh_ffi_test
         "com.android.resolv"