Redo pre-processor block to prevent:
unix.cpp:2543:8: error: macro names must be identifiers

--- unix/unix.cpp.orig	Tue Aug  3 01:14:17 2004
+++ unix/unix.cpp	Thu Jul  7 15:38:35 2011
@@ -2339,12 +2339,13 @@ static bool unix_svga_mode (void)
 static int unix_get_command_line (int *argc, char **argv[])
 {
   is_using_xwin = unix_xwin_mode(*argc, *argv);
-  if(is_using_xwin)
-#ifndef X_DISPLAY_MISSING
-    XWIN_init_povray(argc, argv);  // this changes the command-line args
+  if(is_using_xwin) {
+#if X_DISPLAY_MISSING
+    ; // do nothing
 #else
-    ;  // do nothing
+    XWIN_init_povray(argc, argv);  // this changes the command-line args
 #endif
+  }
   else
   {
     is_using_svga = unix_svga_mode();
@@ -2542,7 +2543,7 @@ int POV_Std_Test_Abort(void)
 *
 ******************************************************************************/
 
-#ifdef UNDERFLOW
+#if 0
 #ifdef exception
 
 int matherr(struct exception *x)