Make _rust_extern_with_linkage_* readonly
Make _rust_extern_with_linkage_* readonly

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