gcc: remove version 4.4.x

That gcc series is old and is not used as the default version for
any of the architectures we support, so this commit gets rid of it.

[Thomas: move the Config.in.legacy option at the right location.]

Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>