input/rewind: move sources out of the "plugins" directory

This is not a plugin.

src/input/Open.cxx

@@ -22,7 +22,7 @@
 #include "Registry.hxx"
 #include "InputPlugin.hxx"
 #include "LocalOpen.hxx"
-#include "plugins/RewindInputPlugin.hxx"
+#include "RewindInputStream.hxx"
 #include "fs/Traits.hxx"
 #include "fs/AllocatedPath.hxx"
 

src/input/RewindInputStream.cxx

@@ -18,8 +18,8 @@
  */
 
 #include "config.h"
-#include "RewindInputPlugin.hxx"
-#include "../ProxyInputStream.hxx"
+#include "RewindInputStream.hxx"
+#include "ProxyInputStream.hxx"
 
 #include <assert.h>
 #include <string.h>

src/input/RewindInputStream.hxx

@@ -24,11 +24,11 @@
  * each decoder plugin peek a portion from the stream).
  */
 
-#ifndef MPD_INPUT_REWIND_HXX
-#define MPD_INPUT_REWIND_HXX
+#ifndef MPD_REWIND_INPUT_STREAM_HXX
+#define MPD_REWIND_INPUT_STREAM_HXX
 
 #include "check.h"
-#include "input/Ptr.hxx"
+#include "Ptr.hxx"
 
 InputStreamPtr
 input_rewind_open(InputStreamPtr is);