package/libecore: do not build anything at patch time

Trying to build anything at patch time will result in a broken
legal-info, as the needed host dependencies are not yet built.

Make that hook a pre-configure hook rather than a post-extract
hook.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Peter Korsgaard <jacmet@uclibc.org>
Cc: Romain Naour <romain.naour@openwide.fr>
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>