Sync linker with internal branch

This change includes dlwarning implementation and
the compatibility greylist for apps targeting pre-N.

Change-Id: Ibf02a07cc58cbbb1a5aef4ac34558c5d43e4305f
Test: Run bionic-unit-tests --gtest_filter=dl*:Dl*
diff --git a/libdl/libdl.arm64.map b/libdl/libdl.arm64.map
index daf5a86..74e029c 100644
--- a/libdl/libdl.arm64.map
+++ b/libdl/libdl.arm64.map
@@ -20,6 +20,7 @@
 
 LIBC_PLATFORM {
   global:
+    android_dlwarning;
     android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;