When enabling compression send 'gzip' as Content-Encoding instead of the
deprecated 'x-gzip'. Acording to RFC2616 clients should handle "x-gzip"
but it seems that at least some Android devices does not.

In general the webserver instead of the CGI should probably do
compression, but this is an easy fix.

PR: www/152202
Reported by: Tom Judge <tom@tomjudge.com>