Add NDK API for getprocdns,setprocdns

The API allows callers to control the default network that is used for
DNS hostname resolution.

Test: atest CtsNetTestCases
      Tests in change I00143cafcd3eb1d71e8d5c7ea9c839a99dc6f4ce
Bug: 171540887
Change-Id: I42f0d9b17b3058f6e10fd2e651278b290f26667f
diff --git a/native/android/libandroid.map.txt b/native/android/libandroid.map.txt
index 85513ca..6d7badb 100644
--- a/native/android/libandroid.map.txt
+++ b/native/android/libandroid.map.txt
@@ -287,6 +287,8 @@
     android_getaddrinfofornetwork; # introduced=23
     android_getprocnetwork; # introduced=31
     android_setprocnetwork; # introduced=23
+    android_getprocdns; # introduced=31
+    android_setprocdns; # introduced=31
     android_setsocknetwork; # introduced=23
     android_res_cancel; # introduced=29
     android_res_nquery; # introduced=29