Fix error pattern

Author: Kimundi

tests/compile-fail/static_is_sized.rs

@@ -4,7 +4,7 @@ extern crate lazy_static;
 lazy_static! {
     pub static ref FOO: str = panic!();
 }
-//^ ERROR `str` does not have a constant size known at compile-time
+//^ ERROR the trait bound `str: std::marker::Sized` is not satisfied
 
 fn main() {
 }