Declare all Rust functions as unnamed_addr. Closes #8957

Author: brson

src/librustc/middle/trans/base.rs

@@ -182,6 +182,8 @@ pub fn decl_fn(llmod: ModuleRef, name: &str, cc: lib::llvm::CallConv, ty: Type)
     };
 
     lib::llvm::SetFunctionCallConv(llfn, cc);
+    // Function addresses in Rust are never significant, allowing functions to be merged.
+    lib::llvm::SetUnnamedAddr(llfn, true);
     return llfn;
 }