package/pkg-utils.mk: rework implementation of extractor-system-dependency
Now that we have the EXTRACTOR_PKG_DEPENDENCY.* variables available,
we can use them to implement extractor-system-dependency: if for a
given archive type, the corresponding EXTRACTOR_PKG_DEPENDENCY.<type>
variable is empty, then it means we need the corresponding extractor
tool to be provided by the system.
Following this, EXTRACTOR_DEPENDENCY_PRECHECKED_EXTENSIONS is no
longer used, so we can drop it from support/dependencies/.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>