syslinux: add support for host-install

This makes it possible to build the syslinux/extlinux installer, so a
bootable USB drive, CompactFlash or SD card can be created by a user
script.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

boot/syslinux/syslinux.mk

@@ -26,4 +26,18 @@ define SYSLINUX_INSTALL_IMAGES_CMDS
 	done
 endef
 
+
+define HOST_SYSLINUX_BUILD_CMDS
+	$(HOST_MAKE_ENV) $(MAKE) -C $(@D)
+endef
+
+define HOST_SYSLINUX_INSTALL_CMDS
+	$(HOST_MAKE_ENV) $(MAKE) -C $(@D) INSTALLROOT=$(HOST_DIR) install
+endef
+
+define HOST_SYSLINUX_CLEAN_CMDS
+	$(HOST_MAKE_ENV) $(MAKE) -C $(@D) clean
+endef
+
 $(eval $(call GENTARGETS))
+$(eval $(call GENTARGETS,host))