Fix for STORM-1854: Linux Viewer crashes on startup after update to Fontconfig 2.9.0

Thanks to Johnnie Carling
https://jira.secondlife.com/browse/STORM-1854?focusedCommentId=325106&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-325106

indra/llwindow/llwindowsdl.cpp

@@ -2621,8 +2621,9 @@ std::vector<std::string> LLWindowSDL::getDynamicFallbackFontList()
 	if (sortpat)
 	{
 		// Sort the list of system fonts from most-to-least-desirable.
+		FcResult fresult;
 		fs = FcFontSort(NULL, sortpat, elide_unicode_coverage,
-				NULL, NULL);
+				NULL, &fresult);
 		FcPatternDestroy(sortpat);
 	}