Lower C.63 to warning. (#2219)

Analyze.default.ruleset

@@ -14,7 +14,7 @@
     <Rule Id="C26116" Action="Error" />
     <Rule Id="C26117" Action="Error" />
     <Rule Id="C26140" Action="Error" />
-    <Rule Id="C26437" Action="Error" />
+    <Rule Id="C26437" Action="Warning" />
     <Rule Id="C26439" Action="Error" />
     <Rule Id="C26441" Action="Error" />
     <Rule Id="C26444" Action="Error" />