Fix dialyzer erts file lookup for releases prior to R16B02

erts.app was introduced in R16B02 so read all beam files from the erts
ebin directory if erts.app file does not exist.

src/rebar_prv_dialyzer.erl

@@ -202,6 +202,8 @@ ebin_to_info(EbinDir, AppName) ->
             Modules = proplists:get_value(modules, AppDetails, []),
             Files = modules_to_files(Modules, EbinDir),
             {IncApps ++ DepApps, Files};
+        {error, enoent} when AppName =:= erts ->
+            {[], ebin_files(EbinDir)};
         _ ->
             Error = io_lib:format("Could not parse ~p", [AppFile]),
             throw({dialyzer_error, Error})
@@ -222,6 +224,11 @@ module_to_file(Module, EbinDir, Ext) ->
             false
     end.
 
+ebin_files(EbinDir) ->
+    Wildcard = "*" ++ code:objfile_extension(),
+    [filename:join(EbinDir, File) ||
+     File <- filelib:wildcard(Wildcard, EbinDir)].
+
 read_plt(_State, Plt) ->
     case dialyzer:plt_info(Plt) of
         {ok, Info} ->