libkmod: use a dup()'d fd for zlib

libkmod: use a dup()'d fd for zlib

The gzdopen() API used, takes ownership of the fd. To make that more
explicit we clear it (-1) as applicable.

Yet again, kmod has explicit API to return the fd to the user - which
currently is used solely when uncompressed, so we're safe.

Regardless - simply duplicate the fd locally and use that with zlib.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>