Remove unnecessary encoding comments

These files do not contain any non-ASCII characters.

Library/Homebrew/extend/ENV/std.rb

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require 'hardware'
 require 'os/mac'
 require 'extend/ENV/shared'

Library/Homebrew/formula_installer.rb

@@ -1,5 +1,3 @@
-# encoding: UTF-8
-
 require 'cxxstdlib'
 require 'exceptions'
 require 'formula'

Library/brew.rb

@@ -1,5 +1,4 @@
 #!/System/Library/Frameworks/Ruby.framework/Versions/Current/usr/bin/ruby -W0
-# encoding: UTF-8
 
 std_trap = trap("INT") { exit! 130 } # no backtrace thanks