Fix execution_direction's type

This fixes a few build errors like these in C++ mode:

  src/gdb/reverse.c: In function ‘void exec_reverse_once(char*, char*, int)’:
  src/gdb/reverse.c:49:34: error: invalid conversion from ‘int’ to ‘exec_direction_kind’ [-fpermissive]
     enum exec_direction_kind dir = execution_direction;
				    ^
  make: *** [reverse.o] Error 1

gdb/ChangeLog:
2015-10-13  Pedro Alves  <palves@redhat.com>

	* infrun.c (restore_execution_direction): New function.
	(fetch_inferior_event): Use it instead of
	make_cleanup_restore_integer.
	(execution_direction): Change type to enum
	exec_direction_kind.
	* infrun.h (execution_direction): Likewise.

gdb/ChangeLog

@@ -1,3 +1,12 @@
+2015-10-13  Pedro Alves  <palves@redhat.com>
+
+	* infrun.c (restore_execution_direction): New function.
+	(fetch_inferior_event): Use it instead of
+	make_cleanup_restore_integer.
+	(execution_direction): Change type to enum
+	exec_direction_kind.
+	* infrun.h (execution_direction): Likewise.
+
 2015-10-13  Pedro Alves  <palves@redhat.com>
 
 	* ada-lang.c (ada_value_primitive_packed_val): Constify

gdb/infrun.c

@@ -3798,6 +3798,17 @@ clean_up_just_stopped_threads_fsms (struct execution_control_state *ecs)
     }
 }
 
+/* A cleanup that restores the execution direction to the value saved
+   in *ARG.  */
+
+static void
+restore_execution_direction (void *arg)
+{
+  enum exec_direction_kind *save_exec_dir = (enum exec_direction_kind *) arg;
+
+  execution_direction = *save_exec_dir;
+}
+
 /* Asynchronous version of wait_for_inferior.  It is called by the
    event loop whenever a change of state is detected on the file
    descriptor corresponding to the target.  It can be called more than
@@ -3815,6 +3826,7 @@ fetch_inferior_event (void *client_data)
   struct cleanup *old_chain = make_cleanup (null_cleanup, NULL);
   struct cleanup *ts_old_chain;
   int was_sync = sync_execution;
+  enum exec_direction_kind save_exec_dir = execution_direction;
   int cmd_done = 0;
   ptid_t waiton_ptid = minus_one_ptid;
 
@@ -3847,7 +3859,7 @@ fetch_inferior_event (void *client_data)
      event.  */
   target_dcache_invalidate ();
 
-  make_cleanup_restore_integer (&execution_direction);
+  make_cleanup (restore_execution_direction, &save_exec_dir);
   execution_direction = target_execution_direction ();
 
   ecs->ptid = do_target_wait (waiton_ptid, &ecs->ws,
@@ -8937,7 +8949,7 @@ clear_exit_convenience_vars (void)
    Set exec-direction / show exec-direction commands
    (returns error unless target implements to_set_exec_direction method).  */
 
-int execution_direction = EXEC_FORWARD;
+enum exec_direction_kind execution_direction = EXEC_FORWARD;
 static const char exec_forward[] = "forward";
 static const char exec_reverse[] = "reverse";
 static const char *exec_direction = exec_forward;

gdb/infrun.h

@@ -74,10 +74,8 @@ enum exec_direction_kind
     EXEC_REVERSE
   };
 
-/* The current execution direction.  This should only be set to enum
-   exec_direction_kind values.  It is only an int to make it
-   compatible with make_cleanup_restore_integer.  */
-extern int execution_direction;
+/* The current execution direction.  */
+extern enum exec_direction_kind execution_direction;
 
 extern void start_remote (int from_tty);