New formula: libssh

Closes Homebrew/homebrew#8909.

[jn: use std_cmake_parameters, style. Note that this is a separate
project from libssh2.]

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

Formula/libssh.rb

@@ -0,0 +1,17 @@
+require 'formula'
+
+class Libssh < Formula
+  url 'http://www.libssh.org/files/0.5/libssh-0.5.2.tar.gz'
+  homepage 'http://www.libssh.org/'
+  md5 '38b67c48af7a9204660a3e08f97ceba6'
+
+  depends_on 'cmake' => :build
+
+  def install
+    mkdir 'build'
+    cd 'build' do
+      system "cmake .. #{std_cmake_parameters}"
+      system "make install"
+    end
+  end
+end