Add XDG_DATA_DIRS to xcursor search path
For XDG Base Directory Specification
The XDG_DATA_HOME is already supported.
This patch adds XDG_DATA_DIRS support.
As specifications:
- $XDG_DATA_DIRS defines the preference-ordered set of base directories to search for data files in addition to the $XDG_DATA_HOME base directory.
- if $XDG_DATA_DIRS is either not set or empty, a value equal to /usr/local/share/:/usr/share/ should be used.
- look in $HOME/.icons (for backwards compatibility) at first.
Related:
!112 (merged)
https://github.com/alacritty/alacritty/issues/4371
https://github.com/flatpak/flatpak/commit/ad87b12264e2795c27a2a4da496b2e3c719767e1
XDG Base Directory Specification
Icon Theme Specification