lshal: fix output streams for testing.

ListCommand does not keep a reference to output
and err streams (for easier mock in testing). Instead,
ListCommand uses out() and err() that calls into
Lshal::out() and err().

Test: lshal
Test: lshal_test
Change-Id: Ie6720833ad513ba5cb1246e34ef96afed5d4373c
diff --git a/cmds/lshal/ListCommand.h b/cmds/lshal/ListCommand.h
index d9d56a3..97c2cdc 100644
--- a/cmds/lshal/ListCommand.h
+++ b/cmds/lshal/ListCommand.h
@@ -72,14 +72,15 @@
     void forEachTable(const std::function<void(Table &)> &f);
     void forEachTable(const std::function<void(const Table &)> &f) const;
 
+    NullableOStream<std::ostream> err() const;
+    NullableOStream<std::ostream> out() const;
+
     Lshal &mLshal;
 
     Table mServicesTable{};
     Table mPassthroughRefTable{};
     Table mImplementationsTable{};
 
-    NullableOStream<std::ostream> mErr;
-    NullableOStream<std::ostream> mOut;
     NullableOStream<std::ofstream> mFileOutput = nullptr;
     TableEntryCompare mSortColumn = nullptr;