In typeck, check for dynamically sized by-value arguments to thunks

A check in trans didn't have a corresponding check in typeck, causing
some programs (to wit, compile-fail/chan-parameterized-args.rs - part of this
commit) to fail with an assertion failure in trans instead of a type error.
Fixed it. In short, arguments that are future thunk arguments (any spawn
arguments, and _ arguments in bind) need to either not contain type params
or type vars, or be by-reference.

Closes #665.

src/comp/util/common.rs

@@ -182,6 +182,19 @@ fn any[T](&fn(&T) -> bool f, &vec[T] v) -> bool {
     ret false;
 }
 
+tag call_kind {
+    kind_call;
+    kind_spawn;
+    kind_bind;
+}
+
+fn call_kind_str(call_kind c) -> str {
+    alt (c) {
+        case (kind_call)  { "Call" }
+        case (kind_spawn) { "Spawn" }
+        case (kind_bind)  { "Bind" }
+    }
+}
 //
 // Local Variables:
 // mode: rust