Update libxml to 2.7.7.

third_party/libxml/include/libxml/xmlversion.h.in

Index: third_party/libxml/include/libxml/xmlversion.h.in
diff --git a/third_party/libxml/include/libxml/xmlversion.h.in b/third_party/libxml/include/libxml/xmlversion.h.in
index 0a9bafaa8a544a5e96e4943f92e52d02eb5ae410..95856541617009e037de8ea0cd8c3469992ff34b 100644
--- a/third_party/libxml/include/libxml/xmlversion.h.in
+++ b/third_party/libxml/include/libxml/xmlversion.h.in
@@ -391,22 +391,74 @@ XMLPUBFUN void XMLCALL xmlCheckVersion(int version);
 #define LIBXML_ZLIB_ENABLED
 #endif
 
+#ifdef __GNUC__
+#ifdef HAVE_ANSIDECL_H
+#include <ansidecl.h>
+#endif
+
 /**
  * ATTRIBUTE_UNUSED:
  *
  * Macro used to signal to GCC unused function parameters
  */
-#ifdef __GNUC__
-#ifdef HAVE_ANSIDECL_H
-#include <ansidecl.h>
-#endif
+
 #ifndef ATTRIBUTE_UNUSED
 #define ATTRIBUTE_UNUSED __attribute__((unused))
 #endif
+
+/**
+ * LIBXML_ATTR_ALLOC_SIZE:
+ *
+ * Macro used to indicate to GCC this is an allocator function
+ */
+
+#ifndef LIBXML_ATTR_ALLOC_SIZE
+# if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)))
+#  define LIBXML_ATTR_ALLOC_SIZE(x) __attribute__((alloc_size(x)))
+# else
+#  define LIBXML_ATTR_ALLOC_SIZE(x)
+# endif
 #else
-#define ATTRIBUTE_UNUSED
+# define LIBXML_ATTR_ALLOC_SIZE(x)
+#endif
+
+/**
+ * LIBXML_ATTR_FORMAT:
+ *
+ * Macro used to indicate to GCC the parameter are printf like
+ */
+
+#ifndef LIBXML_ATTR_FORMAT
+# if ((__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 3)))
+#  define LIBXML_ATTR_FORMAT(fmt,args) __attribute__((__format__(__printf__,fmt,args)))
+# else
+#  define LIBXML_ATTR_FORMAT(fmt,args)
+# endif
+#else
+# define LIBXML_ATTR_FORMAT(fmt,args)
 #endif
 
+#else /* ! __GNUC__ */
+/**
+ * ATTRIBUTE_UNUSED:
+ *
+ * Macro used to signal to GCC unused function parameters
+ */
+#define ATTRIBUTE_UNUSED
+/**
+ * LIBXML_ATTR_ALLOC_SIZE:
+ *
+ * Macro used to indicate to GCC this is an allocator function
+ */
+#define LIBXML_ATTR_ALLOC_SIZE(x)
+/**
+ * LIBXML_ATTR_FORMAT:
+ *
+ * Macro used to indicate to GCC the parameter are printf like
+ */
+#define LIBXML_ATTR_FORMAT(fmt,args)
+#endif /* __GNUC__ */
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */