librustc: Convert ~fn() to proc() everywhere.

src/test/debug-info/lexical-scope-in-unique-closure.rs

@@ -51,7 +51,7 @@ fn main() {
     zzz();
     sentinel();
 
-    let unique_closure: ~fn(int) = |x| {
+    let unique_closure: proc(int) = |x| {
         zzz();
         sentinel();
 

src/test/debug-info/var-captured-in-sendable-closure.rs

@@ -39,7 +39,7 @@ fn main() {
 
     let owned = ~5;
 
-    let closure: ~fn() = || {
+    let closure: proc() = || {
         zzz();
         do_something(&constant, &a_struct.a, owned);
     };