Add formula for GNU Linear Programming Kit

Provides a library and stand-alone tool for solving linear programs (LPs) and
integer linear programs (ILPs). Doesn't depend on anything else.

Formula/glpk.rb

@@ -0,0 +1,12 @@
+require 'brewkit'
+
+class Glpk <Formula
+  url 'http://ftp.gnu.org/gnu/glpk/glpk-4.39.tar.gz'
+  homepage 'http://www.gnu.org/software/glpk/'
+  md5 '95f276ef6c94c6de1eb689f161f525f3'
+
+  def install
+    system "./configure", "--prefix=#{prefix}", "--disable-debug", "--disable-dependency-tracking"
+    system "make install"
+  end
+end