Introduce DL_LOOKUP_FOR_RELOCATE flag for _dl_lookup_symbol_x

This will allow changes in dependency processing during non-lazy
binding, for more precise processing of NODELETE objects: During
initial relocation in dlopen, the fate of NODELETE objects is still
unclear, so objects which are depended upon by NODELETE objects
cannot immediately be marked as NODELETE.

Change-Id: Ic7b94a3f7c4719a00ca8e6018088567824da0658