wavpack: fix compilation on Windows

NarrowPath is needed.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/decoder/plugins/WavpackDecoderPlugin.cxx

@@ -7,6 +7,7 @@
 #include "input/InputStream.hxx"
 #include "pcm/CheckAudioFormat.hxx"
 #include "tag/Handler.hxx"
+#include "fs/NarrowPath.hxx"
 #include "fs/Path.hxx"
 #include "lib/fmt/PathFormatter.hxx"
 #include "lib/fmt/RuntimeError.hxx"
@@ -36,8 +37,9 @@ static WavpackContext *
 WavpackOpenInput(Path path, int flags, int norm_offset)
 {
 	char error[ERRORLEN];
-	auto *wpc = WavpackOpenFileInput(path.c_str(), error,
-					 flags, norm_offset);
+	auto np = NarrowPath(path);
+	auto wpc = WavpackOpenFileInput(np, error,
+					flags, norm_offset);
 	if (wpc == nullptr)
 		throw FmtRuntimeError("failed to open WavPack file \"{}\": {}",
 				      path, error);