GHOST: Fix memory leak in X11 DPI query

The X resource database is to be explicitly destroyed. This fixes 46 bytes
leak per every window DPI query (which happens a lot on window move/resize
and even on areas resize).

Unfortunately, this does not fully fix the leak since the known leak:

  https://bugs.freedesktop.org/show_bug.cgi?id=94604

intern/ghost/intern/GHOST_WindowX11.cpp

@@ -1697,6 +1697,7 @@ getDPIHint()
 				}
 			}
 		}
+		XrmDestroyDatabase(xrdb);
 	}
 
 	/* Fallback to calculating DPI using X reported DPI, set using xrandr --dpi */