Log Message:
screen: Update to 4.8.0

Changelog:
Version 4.8.0 (05/02/2020)
  * Improve startup time by only polling for files to close
  Fixes:
        - Fix for segfault if termcap doesn't have Km entry
        - Make screen exit code be 0 when checking --version
        - Fix potential memory corruption when using OSC 49