Switch to OpenBSD res_random.

Change-Id: Ia971d647832893e9bb4601697132a105524d2f96
diff --git a/libc/Android.mk b/libc/Android.mk
index 0adaff7..2d87ebb 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -636,7 +636,13 @@
     upstream-netbsd/lib/libc/isc/ev_streams.c \
     upstream-netbsd/lib/libc/isc/ev_timers.c \
 
-LOCAL_CFLAGS := \
+# We use the OpenBSD res_random.
+LOCAL_CFLAGS += \
+    -Dres_randomid=__res_randomid
+LOCAL_SRC_FILES += \
+    upstream-openbsd/lib/libc/net/res_random.c \
+
+LOCAL_CFLAGS += \
     $(libc_common_cflags) \
     -DANDROID_CHANGES \
     -DINET6 \