Disable failing InetAddressUtilsTest tests only in host

Bug: 121230364
Test: no testing done
Change-Id: Ib05b181c6a7eb28549ba15a1cbecacb4d79d79c6
diff --git a/tools/libcore_failures.txt b/tools/libcore_failures.txt
index 4dc5ced..3c65b01 100644
--- a/tools/libcore_failures.txt
+++ b/tools/libcore_failures.txt
@@ -200,8 +200,9 @@
   names: ["libcore.libcore.io.FdsanTest#testSocket"]
 },
 {
-  description: "Unexpected failures",
+  description: "Host implementation of android_getaddrinfo differs from device implementation",
   result: EXEC_FAILED,
+  modes: [host],
   bug: 121230364,
   names: [
     "libcore.libcore.net.InetAddressUtilsTest#parseNumericAddress[8]",