sal_rtl_strings unittest depends on sal_textenc library

there's a dlopen of it somewhere in sal's string classes

sal/CppunitTest_sal_rtl_strings.mk

@@ -42,4 +42,9 @@ $(eval $(call gb_CppunitTest_add_linked_libs,sal_rtl_strings,\
     $(gb_STDLIBS) \
 ))
 
+# the test uses the library created by Module_DLL
+$(call gb_CppunitTest_get_target,sal_rtl_strings) : \
+    $(call gb_Library_get_target,sal_textenc)
+
+
 # vim: set noet sw=4 ts=4: