package/petitboot: fix install

buildroot commit 4c8ab13b960edcd290ea5ca7a7e739cb993fb863 added a link
of /usr/sbin/pb-udhcpc in
$(TARGET_DIR)/usr/share/udhcpc/default.script.d/ without creating that
directory first.

Fixes:
http://autobuild.buildroot.net/results/778/77802098355dd99a9e7e6d9178f900a9a8fe72a3/

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

package/petitboot/petitboot.mk

@@ -55,6 +55,7 @@ define PETITBOOT_POST_INSTALL
 		$(TARGET_DIR)/etc/petitboot/boot.d/90-sort-dtb
 	$(INSTALL) -m 0755 -D $(PETITBOOT_PKGDIR)/S15pb-discover \
 		$(TARGET_DIR)/etc/init.d/S15pb-discover
+	mkdir -p $(TARGET_DIR)/usr/share/udhcpc/default.script.d/
 	ln -sf /usr/sbin/pb-udhcpc \
 		$(TARGET_DIR)/usr/share/udhcpc/default.script.d/
 endef