LibCompress: Discard GZip NAME & COMMENT optional strings

We now discard these strings instead of copying them into a String
which we immediately destruct. This should result in both a perf uplift
and lower memory usage.

Userland/Libraries/LibCompress/Gzip.cpp

@@ -118,14 +118,27 @@ size_t GzipDecompressor::read(Bytes bytes)
  m_input_stream.discard_or_error(length);
  }
 
+ auto discard_string = [&]() {
+ char next_char;
+ do {
+ m_input_stream >> next_char;
+ if (m_input_stream.has_any_error()) {
+ set_fatal_error();
+ break;
+ }
+ } while (next_char);
+ };
+
  if (header.flags & Flags::FNAME) {
- String original_filename;
- m_input_stream >> original_filename;
+ discard_string();
+ if (has_any_error())
+ break;
  }
 
  if (header.flags & Flags::FCOMMENT) {
- String comment;
- m_input_stream >> comment;
+ discard_string();
+ if (has_any_error())
+ break;
  }
 
  if (header.flags & Flags::FHCRC) {