add missing dep on jpeg

Change-Id: I0732f23dd9daa0c3a1f138011b0db17b36b729d1
Reviewed-on: https://gerrit.libreoffice.org/32179Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

external/poppler/ExternalProject_poppler.mk

@@ -11,6 +11,10 @@ $(eval $(call gb_ExternalProject_ExternalProject,poppler))
 
 $(eval $(call gb_ExternalProject_use_autoconf,poppler,build))
 
+$(eval $(call gb_ExternalProject_use_externals,poppler,\
+	jpeg \
+))
+
 $(eval $(call gb_ExternalProject_register_targets,poppler,\
 	build \
 ))