Annotate symbols correctly

Currently, tagging a symbol with #apex (# systemapi or # llndk) is not
required when the symbol is in a non-NDK library. However, this is
considered dangerous because such a symbol will automatically be
promoted to NDK APIs when the library is promoted to an NDK library.
When that happens, the native API council won't be able to notice the
promotion because promoting a non-NDK library into an NDK library
doesn't require an update of the map.txt file, but Android.bp only.

To prevent that, we should mandate those tags for Mainline APIs
regardless of whether the library the API belongs to is an NDK library
or not.

Upcoming changes in build/soong will enforce this. This change is to
prepare for the enforcement.

Note that this is a build-time only change. There's no behavior change
at runtime.

Bug: 184712170
Test: m
Change-Id: I18d9722177cd440b939d090b9b653405409a8b57

libnativeloader/libnativeloader.map.txt

@@ -20,13 +20,13 @@
 # that defines the exported interface. Please keep in sync with this list.
 LIBNATIVELOADER_1 {
   global:
-    OpenNativeLibrary;
-    CloseNativeLibrary;
-    OpenNativeLibraryInNamespace;
-    FindNamespaceByClassLoader;
-    FindNativeLoaderNamespaceByClassLoader;
-    CreateClassLoaderNamespace;
-    NativeLoaderFreeErrorMessage;
+    OpenNativeLibrary; # apex
+    CloseNativeLibrary; # apex
+    OpenNativeLibraryInNamespace; # apex
+    FindNamespaceByClassLoader; # apex
+    FindNativeLoaderNamespaceByClassLoader; # apex
+    CreateClassLoaderNamespace; # apex
+    NativeLoaderFreeErrorMessage; # apex
   local:
     *;
 };

sigchainlib/libsigchain.map.txt

@@ -19,7 +19,7 @@ LIBSIGCHAIN_1 {
     # Export no symbols - the only external entry points are libc overrides.
     # Since this section cannot be empty for APEX stubs generation we provide a
     # phony entry.
-    LibsigchainNonexistentFunction;
+    LibsigchainNonexistentFunction; # apex
   local:
     *;
 };