bindexplib: Export symbols from objects even with explicit markup

Drop our `HaveExportedObjects` check before dumping exports for an
object file.  It is possible for only a subset of needed symbols to have
explicit markup, and re-exporting the marked symbols does not hurt.

This leaves no callers of `HaveExportedObjects`, but leave the
method in place anyway because it may be useful in the future.

Fixes #16161.

Source/bindexplib.cxx

@@ -244,9 +244,7 @@ public:
    *----------------------------------------------------------------------
    */
   void DumpObjFile() {
-     if(!HaveExportedObjects()) {
-        this->DumpExternalsObjects();
-     }
+    this->DumpExternalsObjects();
   }
 
   /*