[libxml2] Fix unused function warning in testapi.c

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 9b8ef34dc9c24bfe325edd15aaf0ec00326f04e9
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Fri Feb 4 14:42:16 2022 +0100

    Fix unused function warning in testapi.c

 testapi.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/testapi.c b/testapi.c
index 6f19c6fc..4b091f0c 100644
--- a/testapi.c
+++ b/testapi.c
@@ -382,6 +382,7 @@ static void des_FILE_ptr(int no ATTRIBUTE_UNUSED, FILE *val, int nr ATTRIBUTE_UN
     if (val != NULL) fclose(val);
 }
 
+#ifdef LIBXML_DEBUG_ENABLED
 #define gen_nb_debug_FILE_ptr 2
 static FILE *gen_debug_FILE_ptr(int no ATTRIBUTE_UNUSED, int nr ATTRIBUTE_UNUSED) {
     return(fopen("test.out", "a+"));
@@ -389,6 +390,7 @@ static FILE *gen_debug_FILE_ptr(int no ATTRIBUTE_UNUSED, int nr ATTRIBUTE_UNUSED
 static void des_debug_FILE_ptr(int no ATTRIBUTE_UNUSED, FILE *val, int nr ATTRIBUTE_UNUSED) {
     if (val != NULL) fclose(val);
 }
+#endif
 
 #define gen_nb_const_xmlChar_ptr 5