lib: Clean up vlog use.

Vlog functions assume a vlog module has been defined for the current
translation unit.  Including lib/vlog.h from a header file makes the
vlog API visible even when no vlog module may not have been defined.
This patch removes the two cases in the tree where vlog.h was included
from a header file.

Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

lib/coverage.h

@@ -28,7 +28,6 @@
  * a useful debugging tool. */
 
 #include "ovs-thread.h"
-#include "vlog.h"
 #include "compiler.h"
 
 /* Makes coverage_run run every 5000 ms (5 seconds).

lib/stream.h

@@ -22,11 +22,12 @@
 #include <stdint.h>
 #include <sys/types.h>
 #include "openvswitch/types.h"
-#include "vlog.h"
 #include "socket-util.h"
+#include "util.h"
 
 struct pstream;
 struct stream;
+struct vlog_module;
 
 void stream_usage(const char *name, bool active, bool passive, bool bootstrap);