https://bugs.gentoo.org/913669
fix underlinking with slibtool
--- a/plugins/loaders/cdx/Makefile.am
+++ b/plugins/loaders/cdx/Makefile.am
@@ -18,8 +18,9 @@ gcu_loader_cdx_LTLIBRARIES = cdx.la
 cdx_la_LDFLAGS = -module -avoid-version -no-undefined
 
 cdx_la_LIBADD = \
-		$(gsf_LIBS) \
-		$(top_builddir)/libs/gcu/libgcu-@GCU_API_VER@.la
+		$(gtk_LIBS) $(gsf_LIBS) \
+ 		$(top_builddir)/libs/gcu/libgcu-@GCU_API_VER@.la \
+		$(top_builddir)/libs/gcp/libgcp-@GCU_API_VER@.la
 
 cdx_la_SOURCES =	\
 	cdx.cc
--- a/plugins/loaders/cdxml/Makefile.am
+++ b/plugins/loaders/cdxml/Makefile.am
@@ -17,8 +17,9 @@ gcu_loader_cdxml_LTLIBRARIES = cdxml.la
 cdxml_la_LDFLAGS = -module -avoid-version -no-undefined
 
 cdxml_la_LIBADD = \
-		$(gsf_LIBS) $(goffice_LIBS) \
-		$(top_builddir)/libs/gcu/libgcu-@GCU_API_VER@.la
+ 		$(gtk_LIBS) $(gsf_LIBS) $(goffice_LIBS) \
+		$(top_builddir)/libs/gcu/libgcu-@GCU_API_VER@.la \
+		$(top_builddir)/libs/gcp/libgcp-@GCU_API_VER@.la
 
 cdxml_la_SOURCES =	\
 	cdxml.cc