voro++: migrate from homebrew/science

Closes #16743.

Signed-off-by: FX Coudert <fxcoudert@gmail.com>

Formula/voro++.rb

@@ -0,0 +1,30 @@
+class Voroxx < Formula
+  desc "3D Voronoi cell software library"
+  homepage "http://math.lbl.gov/voro++"
+  url "http://math.lbl.gov/voro++/download/dir/voro++-0.4.6.tar.gz"
+  sha256 "ef7970071ee2ce3800daa8723649ca069dc4c71cc25f0f7d22552387f3ea437e"
+  revision 1
+
+  def install
+    system "make", "install", "PREFIX=#{prefix}"
+    pkgshare.install("examples")
+    mv prefix/"man", share/"man"
+  end
+
+  test do
+    (testpath/"test.cpp").write <<-EOS.undent
+      #include "voro++.hh"
+      double rnd() { return double(rand())/RAND_MAX; }
+      int main() {
+        voro::container con(0, 1, 0, 1, 0, 1, 6, 6, 6, false, false, false, 8);
+        for (int i = 0; i < 20; i++) con.put(i, rnd(), rnd(), rnd());
+        if (fabs(con.sum_cell_volumes() - 1) > 1.e-8) abort();
+        con.draw_cells_gnuplot("test.gnu");
+      }
+    EOS
+    system ENV.cxx, "test.cpp", "-I#{include}/voro++", "-L#{lib}",
+                    "-lvoro++"
+    system "./a.out"
+    assert File.exist?("test.gnu")
+  end
+end