Add libewf package (#3569)

Libewf is a library to access the Expert Witness Compression Format (EWF). This
is a prerequsite for bulk_extractor.

Tested on ARM.

packages/libewf.rb

+require 'package'
+
+class Libewf < Package
+  description 'Libewf is a library to access the Expert Witness Compression Format (EWF)'
+  homepage 'https://github.com/libyal/libewf'
+  version '20140608'
+  source_url 'https://github.com/libyal/libewf/releases/download/20171104/libewf-experimental-20171104.tar.gz'
+  source_sha256 'cf36d3baf3a96dbe566fde55ae7d79fc2e7b998806ab13e0f69915799f19e040'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  def self.build
+    system './configure',
+             "--prefix=#{CREW_PREFIX}",
+             "--libdir=#{CREW_PREFIX}"
+    system 'make'
+  end
+
+  def self.install
+    system 'make', "DESTDIR=#{CREW_DEST_DIR}", 'install'
+  end
+end