Refer to newer standard (with correct half-open output intervals)

src/header/stdlib/lcg48.rs

-//! Helper functions for pseudorandom number generation using LCG, see http://pubs.opengroup.org/onlinepubs/7908799/xsh/drand48.html
+//! Helper functions for pseudorandom number generation using LCG, see https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/functions/drand48.html
 
 use platform::types::*;