Fix/workaround compilation error in dds

CLAMP was conflicting between Common.h and BLI_utildefines.h

Ideally we would use macro from BLI, but it's a bit involved change
to make it working with C++, will keep it for later.

source/blender/imbuf/intern/dds/dds_api.cpp

@@ -25,6 +25,10 @@
  */
 
 
+extern "C" {
+#include "BLI_utildefines.h"
+}
+
 #include <stddef.h>
 #include <dds_api.h>
 #include <Stream.h>