package/imagemagick: add host package

This patch adds the host package for imagemagick.
It comes with a minimal selection of configure options to
compile fast cause it is used only to convert
the image files for the custom linux logo.

Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
[Peter: explicitly disable other configure options like it is done for the
	target variant, add host-pkgconf]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>