Use a timer to avoid polling

The timer will be fired asynchronously to handle
time management flags, while other threads are
searching.

This implementation uses a thread waiting on a
timed condition variable instead of real timers.
This approach allow to reduce platform dependant
code to a minimum and also is the most portable given
that timers libraries are very different among platforms
and also the best ones are not compatible with olds
Windows.

Also retire the now unused polling code.

No functional change.

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

src/misc.cpp

@@ -175,6 +175,39 @@ int cpu_count() {
 }
 
 
+/// timed_wait() waits for msec milliseconds. It is mainly an helper to wrap
+/// conversion from milliseconds to struct timespec, as used by pthreads.
+
+#if defined(_MSC_VER)
+
+void timed_wait(WaitCondition* sleepCond, Lock* sleepLock, int msec) {
+  cond_timedwait(sleepCond, sleepLock, msec);
+}
+
+#else
+
+void timed_wait(WaitCondition* sleepCond, Lock* sleepLock, int msec) {
+
+  struct timeval t;
+  struct timespec abstime;
+
+  gettimeofday(&t, NULL);
+
+  abstime.tv_sec = t.tv_sec + (msec / 1000);
+  abstime.tv_nsec = (t.tv_usec + (msec % 1000) * 1000) * 1000;
+
+  if (abstime.tv_nsec > 1000000000LL)
+  {
+      abstime.tv_sec += 1;
+      abstime.tv_nsec -= 1000000000LL;
+  }
+
+  cond_timedwait(sleepCond, sleepLock, &abstime);
+}
+
+#endif
+
+
 /// prefetch() preloads the given address in L1/L2 cache. This is a non
 /// blocking function and do not stalls the CPU waiting for data to be
 /// loaded from memory, that can be quite slow.