Use getenv instead of $_SERVER for environment variables
Use getenv instead of $_SERVER for environment variables

getenv() is the proper way, and $_SERVER was not working on some
configurations.
Improvement of https://github.com/FreshRSS/FreshRSS/pull/2213

aledeg/FreshRSS,romibi/FreshRSS,aledeg/FreshRSS,romibi/FreshRSS,aledeg/FreshRSS,marienfressinaud/FreshRSS,romibi/FreshRSS,marienfressinaud/FreshRSS,aledeg/FreshRSS,FreshRSS/FreshRSS,Alkarex/FreshRSS,marienfressinaud/FreshRSS,FreshRSS/FreshRSS,Alkarex/FreshRSS,Alkarex/FreshRSS,marienfressinaud/FreshRSS,FreshRSS/FreshRSS,romibi/FreshRSS,FreshRSS/FreshRSS,Alkarex/FreshRSS