add missing dep on oox/helper/helper.hxx

Ultimately, most of the stuff in this header ought to be moved into
comphelper or other "common" module.

Change-Id: Ib31500b2d18f0371efc9f1217aa481367c0abfcc

sc/Library_sc.mk

@@ -40,6 +40,10 @@ $(eval $(call gb_Library_add_defs,sc,\
 	-DSC_INFO_OSVERSION=\"$(OS)\" \
 ))
 
+$(eval $(call gb_Library_use_packages,sc,\
+	oox_inc \
+))
+
 $(eval $(call gb_Library_use_sdk_api,sc))
 
 $(eval $(call gb_Library_use_externals,sc,\