Improve regex for test

gcc/testsuite/ChangeLog:

	* rust/compile/invalid_impl_for.rs: nothing should change in principle

Signed-off-by: Lúcio Boari Fleury <lucboari@gmail.com>

Author: lucbf

gcc/testsuite/rust/compile/invalid_impl_for.rs

@@ -1,4 +1,4 @@
 impl Foo for
-fn main() {// { dg-error "unexpected token ..*. - expected bare function" }
+fn main() {// { dg-error "unexpected token .* - expected bare function" }
 // { dg-error "could not parse type in trait impl" "" { target *-*-* } .-1 }
 }