curl: update to 7.28.1 and enable ipv6

To get this to build we switch from using configure to a premade
makefile. This affects the resulting dll name and will require
relinking any other binaries using the curl dll.

This patch also makes curl use the Windows built-in SSL support
rather than using OpenSSL.

Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Install curl-7.28.1.tar.bz2

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
gnupg: added a release script to build and install gnupg.

When built for Windows gpg expects to find it's helper scripts in the same
directory but the installer places these in the libexec folder so we need
to move these so that 'gpg --refresh-keys' can work.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Install gnupg-1.4.13.tar.gz

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>