libdl: Add symbol searching and loading from archives.

- Load archive symbol tables to support searching of archives
  for symbols.
- Search archive symbols and load the object file that contains
  the symbol.
- Search the global and archives until all remaining unresolved symbols
  are not found. Group the loaded object files in the pending queue.
- Run the object file and loaded dependents as a group before adding to the
  main object list.
- Remove orphaned object files after references are removed.

Updates #3686

cpukit/libdl/rtl-trace.c

@@ -69,7 +69,9 @@ rtems_rtl_trace_shell_command (int argc, char *argv[])
     "load-sect",
     "allocator",
     "unresolved",
-    "cache"
+    "cache",
+    "archives",
+    "dependency"
   };
 
   rtems_rtl_trace_mask set_value = 0;