Fix error messages harder

src/test/compile-fail/alt-vec-mismatch-2.rs

@@ -1,5 +1,5 @@
 fn main() {
     match () {
-        [()] => { } //~ ERROR mismatched type: expected `()` but found a vector pattern
+        [()] => { } //~ ERROR mismatched types: expected `()` but found a vector pattern
     }
 }

src/test/compile-fail/alt-vec-mismatch.rs

@@ -1,6 +1,6 @@
 fn main() {
     match ~"foo" {
-        ['f', 'o', .._] => { } //~ ERROR mismatched type: expected `~str` but found a vector pattern
+        ['f', 'o', .._] => { } //~ ERROR mismatched types: expected `~str` but found a vector pattern
         _ => { }
     }
 }