Seems that on the Android tinderboxes, icudata is needed by helpex

But it built fine locally for me, huh. Oh well.

Change-Id: Icef376a26eb8069eff002b2112a25363b5e18cb3

l10ntools/Executable_helpex.mk

@@ -23,6 +23,7 @@ $(eval $(call gb_Executable_use_externals,helpex,\
 	boost_headers \
 	icu_headers \
     libxml2 \
+	icudata \
     icuuc \
     icui18n \
 ))