Do not add duplicate soinfos to g_default_namespace

The soinfo instances of linker and vdso have been added to g_default_namespace
before init_default_namespace() is called. So init_default_namespace() don't
have to add them a second time.

Test: manual
Change-Id: I29b3da782b1e9445509f45a7698561fc3e19e9a1
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 1393eb5..1e77daf 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -4195,11 +4195,13 @@
   // we also need vdso to be available for all namespaces (if present)
   soinfo* vdso = solist_get_vdso();
   for (auto it : namespaces) {
-    it.second->add_soinfo(ld_android_so);
-    if (vdso != nullptr) {
-      it.second->add_soinfo(vdso);
+    if (it.second != &g_default_namespace) {
+      it.second->add_soinfo(ld_android_so);
+      if (vdso != nullptr) {
+        it.second->add_soinfo(vdso);
+      }
+      // somain and ld_preloads are added to these namespaces after LD_PRELOAD libs are linked
     }
-    // somain and ld_preloads are added to these namespaces after LD_PRELOAD libs are linked
   }
 
   set_application_target_sdk_version(config->target_sdk_version());