Fix scheduler compilation on targets where char is unsigned.

Per discussion with nickm, the `dir` argument should be a int rather
than a signed char.

Fixes bug #14764.

changes/bug14764

@@ -0,0 +1,4 @@
+  o Minor bugfixes (portability):
+    - Fix scheduler compilation on targets where char is unsigned.
+      Fixes bug 14764; bugfix on 0.2.6.2-alpha. Reported by Christian
+      Kujau.

src/or/scheduler.c

@@ -613,7 +613,7 @@ scheduler_touch_channel(channel_t *chan)
  */
 
 void
-scheduler_adjust_queue_size(channel_t *chan, char dir, uint64_t adj)
+scheduler_adjust_queue_size(channel_t *chan, int dir, uint64_t adj)
 {
   time_t now = approx_time();
 

src/or/scheduler.h

@@ -29,7 +29,7 @@ void scheduler_channel_wants_writes(channel_t *chan);
 MOCK_DECL(void,scheduler_release_channel,(channel_t *chan));
 
 /* Notify scheduler of queue size adjustments */
-void scheduler_adjust_queue_size(channel_t *chan, char dir, uint64_t adj);
+void scheduler_adjust_queue_size(channel_t *chan, int dir, uint64_t adj);
 
 /* Notify scheduler that a channel's queue position may have changed */
 void scheduler_touch_channel(channel_t *chan);