Add package for Gnome NetworkManager

Even though it's most commonly used on desktops, this piece of software
also works well on embedded devices.

The package file only resolved mandatory dependencies. Things like
iptables and dnsmasq are only required if 'shared' connections are used,
and have hence not been made hard prerequisites.

There are probably too many i18n related files installed to the target.
That might need some more tweaking.

[Peter: fix Kconfig dependencies, add execinfo patch, fix libgcrypt-config
        path, uClibc build fix]
Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>