Detect the posix unistd.h header file

The getopt function is defined in the unistd.h header file. This header
file is only available on posix compatible systems. For example, on
Windows it's not available when building without mingw.

configure.ac

@@ -157,7 +157,7 @@ AC_CHECK_HEADERS([sys/socket.h linux/types.h linux/irda.h], , , [
 # Checks for header files.
 AC_CHECK_HEADERS([linux/serial.h])
 AC_CHECK_HEADERS([IOKit/serial/ioss.h])
-AC_CHECK_HEADERS([getopt.h])
+AC_CHECK_HEADERS([unistd.h getopt.h])
 AC_CHECK_HEADERS([sys/param.h])
 AC_CHECK_HEADERS([pthread.h])
 AC_CHECK_HEADERS([mach/mach_time.h])

examples/dctool.c

@@ -24,10 +24,12 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 #include <stdio.h>
 #include <signal.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_download.c

@@ -24,9 +24,11 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
 #include <string.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_dump.c

@@ -24,9 +24,11 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
 #include <string.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_fwupdate.c

@@ -24,8 +24,10 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_help.c

@@ -24,8 +24,10 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_list.c

@@ -24,8 +24,10 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_parse.c

@@ -24,9 +24,11 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
 #include <string.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_read.c

@@ -24,8 +24,10 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_scan.c

@@ -24,8 +24,10 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_timesync.c

@@ -24,8 +24,10 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_version.c

@@ -24,8 +24,10 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

examples/dctool_write.c

@@ -24,8 +24,10 @@
 #endif
 
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif