win: set config engine on higher priority than DISPLAY env var
win: set config engine on higher priority than DISPLAY env var

DISPLAY environment variable may set regardless of Elementary/EFL.
Mostly user has no way to switch their intent engine such as "buffer"

Guarantee work application engine with their intended engine first.

@fix

tasn/elementary,tasn/elementary,FlorentRevest/Elementary,rvandegrift/elementary,FlorentRevest/Elementary,rvandegrift/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary