input/smbclient: wrap in MaybeBufferedInputStream

This enables the input buffer for remote files and caches file
contents in MPD.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/376

NEWS

@@ -1,4 +1,6 @@
 ver 0.21.8 (not yet released)
+* input
+  - smbclient: download to buffer instead of throttling transfer
 * output
   - httpd: add missing mutex lock
   - httpd: fix use-after-free bug

src/input/plugins/SmbclientInputPlugin.cxx

@@ -22,6 +22,7 @@
 #include "lib/smbclient/Mutex.hxx"
 #include "../InputStream.hxx"
 #include "../InputPlugin.hxx"
+#include "../MaybeBufferedInputStream.hxx"
 #include "PluginUnavailable.hxx"
 #include "system/Error.hxx"
 #include "util/ASCII.hxx"
@@ -112,8 +113,9 @@ input_smbclient_open(const char *uri,
 		throw MakeErrno(e, "smbc_fstat() failed");
 	}
 
-	return std::make_unique<SmbclientInputStream>(uri, mutex,
-						      ctx, fd, st);
+	return std::make_unique<MaybeBufferedInputStream>
+		(std::make_unique<SmbclientInputStream>(uri, mutex,
+							ctx, fd, st));
 }
 
 size_t