[ST02.1] Add TYPE_CNAME constant to DnsResolver

This would be needed for subsequent patches that synthesizing DNS
packets for testing purpose.

Bug: 139774492
Test: atest DnsPacketTest DnsResolverTest
Change-Id: I5e58f99b09b693f167178e56f008be8b42d9417a
diff --git a/framework/src/android/net/DnsResolver.java b/framework/src/android/net/DnsResolver.java
index 5e637f9..382a9de 100644
--- a/framework/src/android/net/DnsResolver.java
+++ b/framework/src/android/net/DnsResolver.java
@@ -71,12 +71,14 @@
 
     @IntDef(prefix = { "TYPE_" },  value = {
             TYPE_A,
-            TYPE_AAAA
+            TYPE_AAAA,
+            TYPE_CNAME
     })
     @Retention(RetentionPolicy.SOURCE)
     @interface QueryType {}
     public static final int TYPE_A = 1;
     public static final int TYPE_AAAA = 28;
+    public static final int TYPE_CNAME = 5;
 
     @IntDef(prefix = { "FLAG_" }, value = {
             FLAG_EMPTY,