package/opkg: add optional libsolv dependency

opkg configure script supports the --with-libsolv option since v0.3.2.
See [1].

Note that the opkg internal satisfaction solver is beeing deprecated
as of v0.7.0. See the note in changelog [2].

[1] https://git.yoctoproject.org/opkg/commit?id=bc2d3413e7dd61dd0001cc30b7785880c26eada4
[2] https://git.yoctoproject.org/opkg/tree/CHANGELOG.md?h=v0.7.0#n12

Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/opkg/opkg.mk

@@ -44,6 +44,13 @@ else
 OPKG_CONF_OPTS += --disable-bzip2
 endif
 
+ifeq ($(BR2_PACKAGE_LIBSOLV),y)
+OPKG_DEPENDENCIES += libsolv
+OPKG_CONF_OPTS += --with-libsolv
+else
+OPKG_CONF_OPTS += --without-libsolv
+endif
+
 ifeq ($(BR2_PACKAGE_LZ4),y)
 OPKG_DEPENDENCIES += lz4
 OPKG_CONF_OPTS += --enable-lz4