[libxml2] Use NAN/INFINITY if available to init XPath NaN/Inf

[Nick Wellnhofer <nwellnhof src gnome org>]

commit c9925454fd384a17c8c03d358c6778a552e9287b
Author: Sergey Kosukhin <sergey kosukhin mpimet mpg de>
Date:   Wed Jul 6 17:08:26 2022 +0200

    Use NAN/INFINITY if available to init XPath NaN/Inf

 xpath.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/xpath.c b/xpath.c
index 0fa02913..f59ef41d 100644
--- a/xpath.c
+++ b/xpath.c
@@ -490,11 +490,17 @@ double xmlXPathNINF = 0.0;
 ATTRIBUTE_NO_SANITIZE("float-divide-by-zero")
 void
 xmlXPathInit(void) {
+#if defined(NAN) && defined(INFINITY)
+    xmlXPathNAN = NAN;
+    xmlXPathPINF = INFINITY;
+    xmlXPathNINF = -INFINITY;
+#else
     /* MSVC doesn't allow division by zero in constant expressions. */
     double zero = 0.0;
     xmlXPathNAN = 0.0 / zero;
     xmlXPathPINF = 1.0 / zero;
     xmlXPathNINF = -xmlXPathPINF;
+#endif
 }
 
 /**