Correct helpfile localization in sdext

gb_Extension_add_helpfile second parameter is the
path prefix of en-US source file so it must be in
sourcedir and not in CustomTarget.

Change-Id: Icfb4caab7f9e250b377ef3049a8030ab66454f9d

sdext/Extension_presenter.mk

@@ -137,7 +137,7 @@ $(eval $(call gb_Extension_add_files,presenter-screen,registry/data/org/openoffi
     $(call gb_XcuDataTarget_get_target,sdext/source/presenter/registry/data/org/openoffice/Office/ProtocolHandler.xcu) \
 ))
 
-$(eval $(call gb_Extension_add_helpfile,presenter-screen,$(WORKDIR)/CustomTarget/sdext/source/presenter/help/en-US,com.sun.PresenterScreen-$(PLATFORMID)/presenter.xhp,com.sun.PresenterScreen/presenter.xhp))
+$(eval $(call gb_Extension_add_helpfile,presenter-screen,$(SRCDIR)/sdext/source/presenter/help/en-US,com.sun.PresenterScreen-$(PLATFORMID)/presenter.xhp,com.sun.PresenterScreen/presenter.xhp))
 
 $(eval $(call gb_Extension_add_helptreefile,presenter-screen,$(SRCDIR)/sdext/source/presenter/help/en-US,/help.tree,com.sun.PresenterScreen/help.tree,com.sun.PresenterScreen-$(PLATFORMID)))