PR c++/82406 - C++17 error with noexcept function type

	* g++.dg/ext/attrib54.C: New.

From-SVN: r253425

gcc/testsuite/g++.dg/ext/attrib54.C

+// PR c++/82406
+
+class a
+{
+public:
+  template <typename b> void operator() (const b &);
+};
+void c () throw () __attribute__ ((__nonnull__));
+void
+d ()
+{
+  a e;
+  e (c);
+}