The workaround is no longer needed after
https://www.illumos.org/issues/15657

--- Authen-PAM-0.16/PAM.xs.orig
+++ Authen-PAM-0.16/PAM.xs
@@ -37,7 +37,7 @@
 /* this is now determined from configure script */
 
 
-#if defined( sun ) || defined( __hpux )
+#if defined( __hpux )
 
   #define CONST_VOID	void
   #define CONST_STRUCT	struct