New formula: xboard

Closes Homebrew/homebrew#7810.
Closes Homebrew/homebrew#8232.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Formula/xboard.rb

@@ -0,0 +1,21 @@
+require 'formula'
+
+class Xboard < Formula
+  url 'http://ftpmirror.gnu.org/xboard/xboard-4.5.3.tar.gz'
+  homepage 'http://www.gnu.org/software/xboard/'
+  md5 '48a623643fc6ad2b3d1963165bca76dc'
+
+  depends_on 'pkg-config' => :build
+  depends_on 'gettext'
+
+  def install
+    args = ["--prefix=#{prefix}",
+            "--x-include=/usr/X11/include",
+            "--x-lib=/usr/X11/lib",
+            "--disable-zippy"]
+
+    system "./configure", *args
+    system "make"
+    system "make install"
+  end
+end