pt.c (do_type_instantiation): Add complain parm; don't complain if called recursively.

        * pt.c (do_type_instantiation): Add complain parm; don't complain
        if called recursively.
        * cp-tree.h, parse.y: Adjust.

From-SVN: r35498

gcc/testsuite/g++.old-deja/g++.pt/explicit80.C

+// Bug: We were complaining about explicit instantiation of A<T>::B.
+// Build don't link:
+
+template <class T>
+struct A
+{
+ public:
+  ~A() { };
+
+  class B;
+};
+
+class A<int>::B { };
+
+template class A<int>;
+template class A<double>;