Add a test for function pointer text wrapping.

tests/expectations/function_ptr.cpp

@@ -0,0 +1,19 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <ostream>
+#include <new>
+
+using MyCallback = void(*)(uintptr_t a, uintptr_t b);
+
+using MyOtherCallback = void(*)(uintptr_t a,
+                                uintptr_t lot,
+                                uintptr_t of,
+                                uintptr_t args,
+                                uintptr_t and_then_some);
+
+extern "C" {
+
+void my_function(MyCallback a, MyOtherCallback b);
+
+} // extern "C"