SIsections.cpp: gratify compiler because of possible missing include of ctime.h

Observed on build with gcc 12.2.

src/eitd/SIsections.cpp

@@ -26,6 +26,7 @@
 #endif
 #include <stdio.h>
 #include <unistd.h>
+#include <ctime>
 
 #include <dvbsi++/descriptor_tag.h>
 #include <dvbsi++/nvod_reference_descriptor.h>