pkg-config: remove host variant

Remove host-pkg-config in favour of host-pkgconf.
Also remove the sysroot support patch since it's only intended for the
host variant.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>