enable cygwin to compile

[michu]

I need lcd4linux on my windows workstation... It works fine with the NULL and X11 driver and a bit buggy with the png driver. The patch is here

Index: thread.h
===================================================================
--- thread.h    (revision 803)
+++ thread.h    (working copy)
@@ -30,6 +30,21 @@
 #ifndef _THREAD_H_
 #define _THREAD_H_

+#ifndef HAVE_UNION_SEMUN
+union semun
+{
+    int    val;
+    struct semid_ds *buf;
+    unsigned short *array;
+};
+#endif
+
+#ifndef SHM_R
+    #define SHM_R 0400
+#endif
+#ifndef SHM_W
+    #define SHM_W 0660
+#endif

 extern int thread_argc;
 extern char **thread_argv;

I think a check is nessesary, if those 3 .h file exist

#include <cygwin/sem.h>
#include <cygwin/shm.h>
#include <cygwin/ipc.h>

use them in the thread.c file