Fix a redefinition warning for the ERROR macro.

Apparantly, the windows wingdi.h header file already defines the
ERROR macro. By defining the NOGDI macro before including the
windows.h header file, we can prevent the wingdi.h file from being
included and thus avoid the warning. We don't need that header for
anything anyway.

Because the libusb header file includes the windows.h file
explicitly, it needs the same fix.

src/atomics_cobalt.c

@@ -27,6 +27,9 @@
 #include <stdlib.h> // malloc, free
 
 #ifdef HAVE_LIBUSB
+#ifdef _WIN32
+#define NOGDI
+#endif
 #include <libusb-1.0/libusb.h>
 #endif
 

src/context.c

@@ -25,6 +25,7 @@
 #include <string.h>
 
 #ifdef _WIN32
+#define NOGDI
 #include <windows.h>
 #endif
 

src/irda.c

@@ -22,6 +22,7 @@
 #include <stdlib.h> // malloc, free
 #include <stdio.h>	// snprintf
 #ifdef _WIN32
+	#define NOGDI
 	#include <winsock2.h>
 	#include <windows.h>
 	#include <af_irda.h>

src/serial_win32.c

@@ -20,6 +20,8 @@
  */
 
 #include <stdlib.h>
+
+#define NOGDI
 #include <windows.h>
 
 #include "serial.h"