Don't use --debug in Test--post-file.px

Test--post-file.px fails when wget is compiled without debugging support.

Signed-off-by: Lars Wendler <polynomial-c@gentoo.org>
Turn --debug into no-op if compiled without debugging support
configure.ac: update copyright years
wget: move --version copyright year out of the localized string
gnulib: pull submodule forward
URL-decode the filename parameter of Content-Disposition HTTP header if it is encoded
http: aesthetic change
Merge remote-tracking branch 'origin/master' into parallel-wget