xcursor: Support XDG user data dir location

Nowadays ~/.icons is not used anymore as the preferred location for custom
user icon themes; XDG_DATA_HOME/icons (aka ~/.local/share/icons) is what
toolkits like GTK prefer. Prepend that location to the default xcursor path, so
that cursor themes installed there can be used by apps and toolkits that use
libXcursor.

Port of https://cgit.freedesktop.org/xorg/lib/libXcursor/commit/src?id=2263c196cb0dcb8547b378df7b35f83b8b99c01e

xcursor/xcursor.c

@@ -618,7 +618,7 @@ XcursorFileLoadImages (FILE *file, int size)
 #endif
 
 #ifndef XCURSORPATH
-#define XCURSORPATH "~/.icons:/usr/share/icons:/usr/share/pixmaps:~/.cursors:/usr/share/cursors/xorg-x11:"ICONDIR
+#define XCURSORPATH "~/.local/share/icons:~/.icons:/usr/share/icons:/usr/share/pixmaps:"ICONDIR
 #endif
 
 static const char *