Remove current line printing in SMP mode

Was broken and fixing would be too messy.
Now this option is only activated in single thread mode

No functional change

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/thread.h

@@ -87,7 +87,6 @@ struct Thread {
   volatile int activeSplitPoints;
   uint64_t nodes;
   uint64_t betaCutOffs[2];
-  volatile bool printCurrentLineRequest;
   volatile ThreadState state;
   unsigned char pad[64]; // set some distance among local data for each thread
 };