enviroment variable GTK2_RC_FILES ignored

The environment variable GTK2_RC_FILES used to override/specify the GTK2 configuration is ignored by xfsettingsd, for GTK3 applications using the environment variable GTK_THEME the theme is overridden as expected.

Demonstration:

with xfsettingsd running in the background (the application gets the configuration done by xfce4-appearance-settings)

with xfsettingsd running in the background and using the environment variable GTK2_RC_FILES (no changes, xfsettingsd ignores completely the configuration for GTK2 passed with the env var and paints de application again with the configuration done by xfce4-appearance-settings)

with no xfsettingsd running and using the environment variable GTK2_RC_FILES (when xfsettingsd is not running then all the configuration specified by the environment variable is applied as expected)

This does not happen with GTK3, the env var GTK_THEME works no matter if xfsettingsd is running or not.