Merge pull request #426 from cstrouse/add-lz4

Add lz4 (1.7.5) package

packages/lz4.rb

+require 'package'
+
+class Lz4 < Package
+  version '1.7.5'
+  source_url 'https://github.com/lz4/lz4/archive/v1.7.5.tar.gz'
+  source_sha1 'a710a7d45beb0951806d2b98f0c1739107e97c14'
+
+  def self.build
+    if `uname -m`.strip == "x86_64"
+      system "make", "PREFIX=/usr/local", "libdir=/usr/local/lib64"
+    else
+      system "make", "PREFIX=/usr/local", "libdir=/usr/local/lib"
+    end
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install" 
+  end
+end