Define CRYPT_LUKS in crypt-util.h

Also do not include libcryptsetup.h directly, but only through crypt-util.h.
This way we do not have to repeat the define in every file where it is used.

src/basic/crypt-util.h

@@ -23,6 +23,11 @@
 
 #include "macro.h"
 
+/* libcryptsetup define for any LUKS version, compatible with libcryptsetup 1.x */
+#ifndef CRYPT_LUKS
+#define CRYPT_LUKS NULL
+#endif
+
 DEFINE_TRIVIAL_CLEANUP_FUNC(struct crypt_device *, crypt_free);
 
 void cryptsetup_log_glue(int level, const char *msg, void *usrptr);