Log Message:
mpv: Update multimedia/mpv to 0.27.1

pkgsrc changes:
 - Remove patches/patch-player_lua_ytdl__hook.lua, no longer needed because it
   is present since 0.27.1 and 0.28.1 mpv releases

Changes:
0.27.1
======
This releaes fixes CVE-2018-6360.

Fixes and Minor Enhancements
----------------------------
 - ytdl_hook:  whitelist protocols from urls retrieved from youtube-dl (#5456)