Remove @internal API from libandroidicu headers

- libandroidicu will now exclude anything marked with @internal.

Bug: 120420009
Test: m droid
Change-Id: I45d81243306cf1eaf6d8c8b1496df5f6142c1c4e
diff --git a/libandroidicu/include/uconfig_local.h b/libandroidicu/include/uconfig_local.h
index b016fcd..0f743bc 100644
--- a/libandroidicu/include/uconfig_local.h
+++ b/libandroidicu/include/uconfig_local.h
@@ -23,5 +23,4 @@
 #define U_HIDE_DRAFT_API 1
 #define U_HIDE_DEPRECATED_API 1
 #define U_SHOW_CPLUSPLUS_API 0
-// TODO(b/120420009): Enable this flag. Currently, libandroidicu can't be built with this flag.
-// #define U_HIDE_INTERNAL_API 1
+#define U_HIDE_INTERNAL_API 1