Configuring of dub for the application reading enviroment variable

[MGW via Digitalmars-d-learn]

My STARTING application shall read the enviroment variable.
For example MY_VARIABLE= "I'm Gena".
The MY_VARIABLE variable needs to be set in dub.json so
what she would be visible in case of start of my application.
Purpose: to set LD_LIBRARY_PATH having specified a certain 
directory in dub packet.

Please, write an example of dub.json for it.