rework previous patch to avoid changing the inline code

apt-pkg/contrib/fileutl.cc

@@ -890,6 +890,11 @@ bool FileFd::OpenDescriptor(int Fd, unsigned int const Mode, CompressMode Compre
    std::vector<APT::Configuration::Compressor> const compressors = APT::Configuration::getCompressors();
    std::vector<APT::Configuration::Compressor>::const_iterator compressor = compressors.begin();
    std::string name;
+
+   // compat with the old API
+   if (Mode == ReadOnlyGzip && Compress == None)
+      Compress = Gzip;
+
    switch (Compress)
    {
    case None: name = "."; break;

apt-pkg/contrib/fileutl.h

@@ -108,10 +108,7 @@ class FileFd
    bool OpenDescriptor(int Fd, unsigned int const Mode, CompressMode Compress, bool AutoClose=false);
    bool OpenDescriptor(int Fd, unsigned int const Mode, APT::Configuration::Compressor const &compressor, bool AutoClose=false);
    inline bool OpenDescriptor(int Fd, unsigned int const Mode, bool AutoClose=false) {
-      if (Mode == ReadOnlyGzip)
-         return OpenDescriptor(Fd, Mode, Gzip, AutoClose);
-      else
-         return OpenDescriptor(Fd, Mode, None, AutoClose);
+      return OpenDescriptor(Fd, Mode, None, AutoClose);
    };
    bool Close();
    bool Sync();