Avoid zombie by less if LESSOPEN is used

--- less-458/main.c.orig        2013-04-04 19:55:05.000000000 +0300
+++ less-458/main.c     2014-05-28 14:00:04.586513424 +0300
@@ -17,6 +17,10 @@
 #include <windows.h>
 #endif

+#ifndef WIN32
+#include <signal.h>
+#endif
+
 public char *  every_first_cmd = NULL;
 public int     new_file;
 public int     is_tty;
@@ -106,6 +110,13 @@
        GetConsoleTitle(consoleTitle, sizeof(consoleTitle)/sizeof(char));
 #endif /* WIN32 */

+#ifndef WIN32
+       /*
+        * Ignore SIGCHLD foor avoid zombies when LESSOPEN is used
+        */
+       signal(SIGCHLD, SIG_IGN);
+#endif /* WIN32 */
+
        /*
         * Process command line arguments and LESS environment arguments.
         * Command line arguments override environment arguments.