Predefine all local functions before codegen
Predefine all local functions before codegen

Otherwise only calls to previously codegened functions use relative
addressing instead of the GOT

Fixes #692

aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust