Update elixir from 1.6.4 to 1.9.1 (#3522)

Tested on ARM.

packages/elixir.rb

@@ -2,31 +2,22 @@ require 'package'
 
 class Elixir < Package
   description 'Elixir is a dynamic, functional language designed for building scalable and maintainable applications.'
-  homepage 'http://elixir-lang.org/'
-  version '1.6.4'
-  source_url 'https://github.com/elixir-lang/elixir/releases/download/v1.6.4/Precompiled.zip'
-  source_sha256 '3a081c07d8ea2ce6620201e2689ce1fac0ee937ba5c13670cbaa40349e1581ab'
+  homepage 'https://elixir-lang.org/'
+  version '1.9.1'
+  source_url 'https://github.com/elixir-lang/elixir/releases/download/v1.9.1/Precompiled.zip'
+  source_sha256 '17e43cb1627a0fa5625bc370cec0964ad6471ef242f1549e316db73c0d94fcc6'
 
   binary_url ({
-    aarch64: 'https://dl.bintray.com/chromebrew/chromebrew/elixir-1.6.4-chromeos-armv7l.tar.xz',
-     armv7l: 'https://dl.bintray.com/chromebrew/chromebrew/elixir-1.6.4-chromeos-armv7l.tar.xz',
-       i686: 'https://dl.bintray.com/chromebrew/chromebrew/elixir-1.6.4-chromeos-i686.tar.xz',
-     x86_64: 'https://dl.bintray.com/chromebrew/chromebrew/elixir-1.6.4-chromeos-x86_64.tar.xz',
   })
   binary_sha256 ({
-    aarch64: '364edfd964978f230f46721455665d17f6a09a6e7625b20f7fd504cb0208feba',
-     armv7l: '364edfd964978f230f46721455665d17f6a09a6e7625b20f7fd504cb0208feba',
-       i686: '65fb9c5bd16fdceb421200ad88d1aa7fc6a1facaef7fac3f054c12770582533e',
-     x86_64: '1d185f98a47c2924ba747521bf46781bc36846953cfa8a81818f39f03c7d6013',
   })
 
   depends_on 'erlang'
   depends_on 'unzip' => :build
 
   def self.install
-    system "mkdir -p #{CREW_DEST_PREFIX}"
-    system "mkdir -p #{CREW_DEST_PREFIX}/share"
-    system "mkdir -p #{CREW_DEST_LIB_PREFIX}"
+    FileUtils.mkdir_p "#{CREW_DEST_PREFIX}/share"
+    FileUtils.mkdir_p "#{CREW_DEST_LIB_PREFIX}"
     system "cp -r bin/ #{CREW_DEST_PREFIX}"
     system "cp -r lib/* #{CREW_DEST_LIB_PREFIX}"
     system "cp -r man/ #{CREW_DEST_PREFIX}/share"