Add formula for dtach.

Formula/dtach.rb

@@ -0,0 +1,23 @@
+require 'formula'
+
+class Dtach <Formula
+  url 'http://downloads.sourceforge.net/project/dtach/dtach/0.8/dtach-0.8.tar.gz'
+  homepage 'http://dtach.sourceforge.net/'
+  md5 'ec5999f3b6bb67da19754fcb2e5221f3'
+
+  def install
+    system "./configure", "--prefix=#{prefix}", "--disable-debug", "--disable-dependency-tracking"
+    
+    # Does #include <config.h> instead of #include "config.h"
+    # so it needs . in the include path.
+    ENV.append "CFLAGS", "-I."
+
+    # Use our own flags, thanks.
+    inreplace "Makefile", /^CC = .*$/, ""
+    inreplace "Makefile", /^CFLAGS = .*$/, ""
+    inreplace "Makefile", /^LIBS = .*$/, ""
+    
+    system "make"
+    bin.install "dtach"
+  end
+end