LibArchive: Use read_entire_buffer for reading extended headers

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=53913

Userland/Libraries/LibArchive/TarStream.h

@@ -80,7 +80,7 @@ inline ErrorOr<void> TarInputStream::for_each_extended_header(F func)
 
     auto header_size = TRY(header().size());
     ByteBuffer file_contents_buffer = TRY(ByteBuffer::create_zeroed(header_size));
-    VERIFY(TRY(file_stream.read(file_contents_buffer)).size() == header_size);
+    TRY(file_stream.read_entire_buffer(file_contents_buffer));
 
     StringView file_contents { file_contents_buffer };