Display (Linux): show brand of Xserver in WM section (#1888)

* Display: add server vendor string

* Display (X11): fetch server vendor string using XCB/Xlib

* WM: show server vendor string when not empty

* Display (XCB): use proper string helper function

* Display (X11): shorten "The X.Org Foundation" to "Xorg"

src/modules/wm/wm.c

@@ -42,6 +42,13 @@ void ffPrintWM(FFWMOptions* options)
             putchar(')');
         }
 
+        if(result->serverVendor.length > 0)
+        {
+            fputs(" [", stdout);
+            ffStrbufWriteTo(&result->serverVendor, stdout);
+            putchar(']');
+        }
+
         if(pluginName.length > 0)
         {
             fputs(" (with ", stdout);