Add libksba (1.3.5) package

Libksba is a library to make the tasks of working with X.509
certificates, CMS data and related objects more easy.

Tested as working on Samsung XE50013-K01US (x86_64). All tests passing.
https://gist.github.com/cstrouse/df284228dfb306473b1df46de458a1e6

packages/libksba.rb

+require 'package'
+
+class Libksba < Package
+  version '1.3.5'
+  source_url 'https://www.gnupg.org/ftp/gcrypt/libksba/libksba-1.3.5.tar.bz2'
+  source_sha1 'a98385734a0c3f5b713198e8d6e6e4aeb0b76fde'
+
+  depends_on 'npth'
+
+  def self.build
+    system './configure --prefix=/usr/local'
+    system 'make'
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install" 
+  end
+end