build,ib: add STRIP_ABI option for manifest

The ImageBuilder `make manifest` prints all installed packages. This
function can be used to create a list of package and corresponding
package versions before attempting image creation.

When called with `--strip-abi` OPKG can automatically strip attached
ABIVersions from package names. Make this function accessible for the
ImageBuilder by adding a `STRIP_ABI` variable.

Signed-off-by: Paul Spooren <mail@aparcar.org>

target/imagebuilder/files/Makefile

@@ -54,6 +54,7 @@ Print manifest:
 
 	make manifest PROFILE="<profilename>" # override the default target profile
 	make manifest PACKAGES="<pkg1> [<pkg2> [<pkg3> ...]]" # include extra packages
+	make manifest STRIP_ABI=1 # remove ABI version from printed package names
 
 endef
 $(eval $(call shexport,Helptext))
@@ -129,7 +130,7 @@ _call_manifest: FORCE
 	mkdir -p $(TARGET_DIR) $(BIN_DIR) $(TMP_DIR) $(DL_DIR)
 	$(MAKE) package_reload >/dev/null
 	$(MAKE) package_install >/dev/null
-	$(OPKG) list-installed
+	$(OPKG) list-installed $(if $(STRIP_ABI),--strip-abi)
 
 package_index: FORCE
 	@echo >&2