Add a profile.d file for XDG Base Directory Specification

We declare most of the XDG environment variables for this spec:
- XDG_CONFIG_HOME
- XDG_DATA_HOME
- XDG_CONFIG_DIRS
- XDG_DATA_DIRS
- XDG_CACHE_HOME

I'm not yet sure what to do with XDG_RUNTIME_DIR.

data/etc/profile.d/xdg_basedirs.sh

@@ -0,0 +1,20 @@
+#
+# Haiku setup for
+# XDG Base Directory Specification
+#
+# http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
+
+export XDG_CONFIG_HOME="`finddir B_USER_SETTINGS_DIRECTORY`"
+
+export XDG_DATA_HOME="`finddir B_USER_NONPACKAGED_DATA_DIRECTORY`"
+
+export XDG_CONFIG_DIRS="`finddir B_SYSTEM_SETTINGS_DIRECTORY`"
+# XXX:B_USER_ETC_DIRECTORY?
+
+export XDG_DATA_DIRS="`finddir B_SYSTEM_NONPACKAGED_DATA_DIRECTORY`:\
+`finddir B_SYSTEM_DATA_DIRECTORY`"
+
+export XDG_CACHE_HOME="`finddir B_USER_CACHE_DIRECTORY`"
+
+# XXX:TODO
+#export XDG_RUNTIME_DIR="`finddir B_USER_VAR_DIRECTORY`/tmp"