[libxml2] Add XML_DEPRECATED macro

[Nick Wellnhofer <nwellnhof src gnome org>]

commit a2fe74c08a9bd03cf5515b9e44d2005538b9f619
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sun Feb 20 18:19:27 2022 +0100

    Add XML_DEPRECATED macro
    
    __attribute__((deprecated)) is available since at least GCC 3.1, so an
    exact version check is probably unnecessary.

 include/libxml/xmlversion.h.in | 18 ++++++++++++++++++
 testapi.c                      |  3 +++
 2 files changed, 21 insertions(+)
---
diff --git a/include/libxml/xmlversion.h.in b/include/libxml/xmlversion.h.in
index f9f79a2f..b1d2a208 100644
--- a/include/libxml/xmlversion.h.in
+++ b/include/libxml/xmlversion.h.in
@@ -456,6 +456,15 @@ XMLPUBFUN void XMLCALL xmlCheckVersion(int version);
 # define LIBXML_ATTR_FORMAT(fmt,args)
 #endif
 
+#ifndef XML_DEPRECATED
+#  ifdef IN_LIBXML
+#    define XML_DEPRECATED
+#  else
+/* Available since at least GCC 3.1 */
+#    define XML_DEPRECATED __attribute__((deprecated))
+#  endif
+#endif
+
 #else /* ! __GNUC__ */
 /**
  * ATTRIBUTE_UNUSED:
@@ -475,6 +484,15 @@ XMLPUBFUN void XMLCALL xmlCheckVersion(int version);
  * Macro used to indicate to GCC the parameter are printf like
  */
 #define LIBXML_ATTR_FORMAT(fmt,args)
+/**
+ * XML_DEPRECATED:
+ *
+ * Macro used to indicate that a function, variable, type or struct member
+ * is deprecated.
+ */
+#ifndef XML_DEPRECATED
+#define XML_DEPRECATED
+#endif
 #endif /* __GNUC__ */
 
 #ifdef __cplusplus
diff --git a/testapi.c b/testapi.c
index 4b091f0c..3a4dc2fe 100644
--- a/testapi.c
+++ b/testapi.c
@@ -8,6 +8,9 @@
  * daniel veillard com
  */
 
+/* Disable deprecation warnings */
+#define XML_DEPRECATED
+
 #include "libxml.h"
 #include <stdio.h>