package/pkg-utils.mk: add extractor-pkg-dependency macro

To extract some archive types, if the extracting tool is not available
on the system where Buildroot runs on, we build it using a Buildroot
host package.

Such dependencies are currently explicitly handled by the
inner-generic-package macro, but in fact we also need to handle them
in all places where the "suitable-extractor" macro is invoked, and
some packages invoke it directly. Otherwise, such packages may be
missing a dependency to the appropriate host Buildroot package
building the extracting tool they need. An example is gettext-tiny,
whose source code is a gzip-compressed tarball, but in addition
manually extracts a xz-compressed tarball.

This extractor-pkg-dependency macro will be used in follow-up commits
to ensure all the packages that use suitable-extractor properly add
the correct dependencies.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/pkg-utils.mk

@@ -46,6 +46,14 @@ INFLATE.tar  = cat
 # suitable-extractor(filename): returns extractor based on suffix
 suitable-extractor = $(INFLATE$(suffix $(1)))
 
+EXTRACTOR_PKG_DEPENDENCY.lzma = $(BR2_XZCAT_HOST_DEPENDENCY)
+EXTRACTOR_PKG_DEPENDENCY.xz   = $(BR2_XZCAT_HOST_DEPENDENCY)
+EXTRACTOR_PKG_DEPENDENCY.lz   = $(BR2_LZIP_HOST_DEPENDENCY)
+
+# extractor-pkg-dependency(filename): returns a Buildroot package
+# dependency needed to extract file based on suffix
+extractor-pkg-dependency = $(EXTRACTOR_PKG_DEPENDENCY$(suffix $(1)))
+
 # extractor-system-dependency(filename): returns the name of the tool
 # needed to extract 'filename', and is meant to be used with
 # DL_TOOLS_DEPENDENCIES, in order to check that the necesary tool is