Add LLNDK liblog stub library for the VNDK

This replaces the liblog_vndk_headers with a true stub library that
exports the vndk headers, and exports the vndk-specific set of symbols.

Test: generated NDK stub maps are the same before/after
Test: aosp_arm; m -j
Test: Enable BOARD_VNDK_VERSION on aosp_arm; m -j (with other changes)
Change-Id: I9037241963b3872a3bc7cf7ab36a70dd4ddcf9bc
diff --git a/liblog/Android.bp b/liblog/Android.bp
index bb8c3af..bc262db 100644
--- a/liblog/Android.bp
+++ b/liblog/Android.bp
@@ -107,14 +107,16 @@
     license: "NOTICE",
 }
 
-cc_library_headers {
-    name: "liblog_vndk_headers",
-    export_include_dirs: ["include_vndk"],
-}
-
 ndk_library {
     name: "liblog.ndk",
     symbol_file: "liblog.map.txt",
     first_version: "9",
     unversioned_until: "current",
 }
+
+llndk_library {
+    name: "liblog.llndk",
+    symbol_file: "liblog.map.txt",
+    unversioned: true,
+    export_include_dirs: ["include_vndk"],
+}