vclplug_svp build error with --enable-headless

Hello,

i need this to unbreak --enable-headless compilation (still compiling) 
with latest master but it puzzles me the other vclplug entries doesn't 
need the same check, any hint on what --enable-headless is doing wrong 
since this does not break other GUIBASEs?

diff --git a/Repository.mk b/Repository.mk
index c6a779d..97bcece 100644
--- a/Repository.mk
+++ b/Repository.mk
@@ -431,7 +431,7 @@ $(eval $(call gb_Helper_register_libraries,OOOLIBS, \
     vclplug_tde \
     vclplug_kde \
     vclplug_kde4 \
-    vclplug_svp \
+    $(if $(filter unx,$(GUIBASE)),vclplug_svp) \
 ))

 ifneq (,$(filter ANDROID IOS,$(OS)))

CC'ing Marcos since he is currently hacking in this area.

thanks,
riccardo