EPL: fix build with incomplete libxml2 library

HAVE_LIBXML2 can be set while PARSE_XDD is unset, resulting in missing
functions and linker errors.

Bug: 15419
Change-Id: I0aa20a80080d159bfb6eebccc503b66cc148f7f8
Reviewed-on: https://code.wireshark.org/review/31715
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Roland Knall <rknall@gmail.com>

epan/dissectors/packet-epl-profile-parser.c

@@ -298,11 +298,6 @@ cleanup:
 
 #ifdef PARSE_XDD
 
-void
-epl_xdd_init(void)
-{
-}
-
 struct profile *
 epl_xdd_load(struct profile *profile, const char *xml_file)
 {
@@ -570,7 +565,17 @@ populate_object_list(xmlNodeSetPtr nodes, void *_profile)
 }
 
 
-#endif /* PARSE_XDD */
+#else  /* ! PARSE_XDD */
+
+#ifdef HAVE_LIBXML2
+struct profile *
+epl_xdd_load(struct profile *profile _U_, const char *xml_file _U_)
+{
+	return NULL;
+}
+#endif  /* HAVE_LIBXML2 */
+
+#endif  /* ! PARSE_XDD */
 
 /**
  * A sorted array keyed by intervals

epan/dissectors/packet-epl.c

@@ -6180,9 +6180,6 @@ proto_register_epl(void)
 	epl_profiles_by_nodeid = wmem_map_new(wmem_epan_scope(), g_direct_hash, g_direct_equal);
 	epl_profiles_by_address = wmem_map_new(wmem_epan_scope(), epl_address_hash, epl_address_equal);
 
-#ifdef HAVE_LIBXML2
-	epl_xdd_init();
-#endif
 	epl_eds_init();
 
 	prefs_register_filename_preference(epl_module, "default_profile", "Default Profile to use if no specific profiles exist",

epan/dissectors/packet-epl.h

@@ -89,7 +89,6 @@ subobject_equal(gconstpointer _a, gconstpointer _b)
 	    && g_str_equal(a->name, b->name);
 }
 
-void epl_xdd_init(void);
 struct profile *epl_xdd_load(struct profile *profile, const char *xml_file);
 
 void epl_eds_init(void);