Use art_defaults in libnative*, for consistency.

Also change to //art:__submodules__ for consistent internal visibility, and
some TODO comment corrections.

Test: m WITH_TIDY=1
Test: build & boot
Test: atest art/libnativeloader/test (no new errors, but existing ones on arm64 - b/142896688)
Test: (atest art/libnativebridge/tests doesn't work at all, but that's not new - b/142897320)
Bug: 137364733
Bug: 133140750
Change-Id: If9ddb5a597eea3606342c3625dcdb3bcf5d19041
diff --git a/libnativebridge/Android.bp b/libnativebridge/Android.bp
index 2dd92d1..f2db117 100644
--- a/libnativebridge/Android.bp
+++ b/libnativebridge/Android.bp
@@ -1,9 +1,6 @@
 cc_defaults {
     name: "libnativebridge-defaults",
-    cflags: [
-        "-Werror",
-        "-Wall",
-    ],
+    defaults: ["art_defaults"],
     cppflags: [
         "-fvisibility=protected",
     ],
@@ -22,9 +19,8 @@
     name: "libnativebridge",
     defaults: ["libnativebridge-defaults"],
     visibility: [
-        "//art:__subpackages__",
-        // TODO(b/133140750): Clean this up.
         "//frameworks/base/cmds/app_process",
+        // TODO(b/133140750): Clean this up.
         "//frameworks/base/native/webview/loader/libwebviewchromium_loader",
     ],