rtti.c (emit_tinfo_decl): Call import_export_decl.

        * rtti.c (emit_tinfo_decl): Call import_export_decl.
        * decl2.c (import_export_decl): Set DECL_NOT_REALLY_EXTERN on
        tinfo decls by default.  Don't mess with the builtins.

From-SVN: r53417

gcc/testsuite/g++.dg/abi/rtti1.C

+// Test that we don't emit the type_info for a polymorphic class other than
+// with the vtable.
+
+struct A {
+  virtual ~A();
+};
+
+void f ()
+{
+  throw A();
+}
+
+// { dg-final { scan-assembler-dem-not {typeinfo for A[: \t\n]} } }