Add libmnl package

packages/libmnl.rb

+require 'package'
+
+class Libmnl < Package
+  description 'libmnl is a minimalistic user-space library oriented to Netlink developers.'
+  homepage 'https://www.netfilter.org/projects/libmnl/'
+  version '1.0.4'
+  source_url 'https://www.netfilter.org/projects/libmnl/files/libmnl-1.0.4.tar.bz2'
+  source_sha256 '171f89699f286a5854b72b91d06e8f8e3683064c5901fb09d954a9ab6f551f81'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  def self.build
+    system "./configure --prefix=#{CREW_PREFIX} --libdir=#{CREW_LIB_PREFIX}"
+    system "make"
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+  end
+end