Fix stupid glitch rendering logbuffer capabilities useless

Unfortunately, this was present even in the initial public
release 58ec40f9

This issue should have had no production impact, but it made hunting
down bugs unnecessary hard.

src/fellow_log.c

@@ -208,7 +208,7 @@ enum lbuf_state_e {
 
 #define LBUF_CAN_REF	1	// ref this log in header, write head
 #define LBUF_CAN_LOGREG (1<<1)	// write data after block 0 in log region
-#define LBUF_CAN_FLUSH	(1<<1)	// write data after block 0 outside log region
+#define LBUF_CAN_FLUSH	(1<<2)	// write data after block 0 outside log region
 
 #define C(x) (LBUF_CAN_ ## x)