tree decl stored during LGEN does not map to a symtab_node during WPA

[Erick Ochoa]

> I'm not too familiar with it but I think you're supposed to stream encoded
> symtab references during LGEN/WPA,

Thanks Richard, this happened to be the solution. I am now using
lto_symtab_encoder_t to encode the declarations during LGEN and decode
them during WPA.

Are there any more limitations of using stream_write_tree that one
should be aware of? Now I am looking into storing trees of the type
STRING_CST and I think this might be causing me a problem at WPA time.
I think it segfaults at the moment of creating the process, but I
still need more time to investigate. Perhaps you might know if storing
STRING_CST trees has to be handled in a special way? Not sure if it
also has something to do with LTO file sections. The tree is used to
initialize a global static variable.

Thanks!