hooklib: Split out of util

This is distinct from capnhook's hooklib, although the intent is
the same. Hopefully these two libraries sharing a name won't get
too confusing...

cardhook/dllmain.c

@@ -5,9 +5,9 @@
 #include "hook/process.h"
 
 #include "hooklib/serial.h"
+#include "hooklib/spike.h"
 
 #include "util/dprintf.h"
-#include "util/spike.h"
 
 static process_entry_t app_startup;