rootfs: remove unnecessary and potentially harmful force flags from opkg call

Especially --force-overwrite and --force-depends will often lead to broken
images; it's better to fail the build in such cases than to silently ignore
the errors.

Instead, ignore errors in the per-device rootfs opkg remove command, so
the build doesn't break when packages can't be removed because of
dependencies.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

include/image.mk

@@ -288,7 +288,7 @@ target-dir-%: FORCE
 	-mv $(mkfs_cur_target_dir)/etc/opkg $(mkfs_cur_target_dir).opkg
 	echo 'src default file://$(PACKAGE_DIR_ALL)' > $(mkfs_cur_target_dir).conf
 	$(if $(mkfs_packages_remove), \
-		$(call opkg,$(mkfs_cur_target_dir)) remove \
+		-$(call opkg,$(mkfs_cur_target_dir)) remove \
 			$(mkfs_packages_remove))
 	$(if $(call opkg_package_files,$(mkfs_packages_add)), \
 		$(opkg_target) update && \