Clean up ugly usage of the g_nativeLibDir global. Now it's local in VulkanLoader.

Common/File/AndroidStorage.cpp

@@ -368,6 +368,5 @@ const char *Android_ErrorToString(StorageError error) {
 // Very hacky.
 std::string g_extFilesDir = "(IF YOU SEE THIS THERE'S A BUG)";
 std::string g_externalDir = "(IF YOU SEE THIS THERE'S A BUG (2))";
-std::string g_nativeLibDir = "(IF YOU SEE THIS THERE'S A BUG (3))";
 
 #endif