xvid: modernize, https, sha256

Closes Homebrew/homebrew#37627.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Formula/xvid.rb

@@ -1,11 +1,9 @@
-require 'formula'
-
 class Xvid < Formula
-  homepage 'http://www.xvid.org'
-  url 'http://fossies.org/unix/privat/xvidcore-1.3.3.tar.gz'
+  homepage "http://www.xvid.org"
+  url "https://fossies.org/unix/privat/xvidcore-1.3.3.tar.gz"
   # Official download takes a long time to fail, so set it as the mirror for now
-  mirror 'http://downloads.xvid.org/downloads/xvidcore-1.3.3.tar.gz'
-  sha1 '465763c92679ca230526d4890d17dbf6d6974b08'
+  mirror "http://downloads.xvid.org/downloads/xvidcore-1.3.3.tar.gz"
+  sha256 "9e6bb7f7251bca4615c2221534d4699709765ff019ab0366609f219b0158499d"
 
   bottle do
     cellar :any
@@ -16,11 +14,25 @@ class Xvid < Formula
   end
 
   def install
-    cd 'build/generic' do
+    cd "build/generic" do
       system "./configure", "--disable-assembly", "--prefix=#{prefix}"
       ENV.j1 # Or make fails
       system "make"
-      system "make install"
+      system "make", "install"
     end
   end
+
+  test do
+    (testpath/"test.cpp").write <<-EOS.undent
+      #include <xvid.h>
+      #define NULL 0
+      int main() {
+        xvid_gbl_init_t xvid_gbl_init;
+        xvid_global(NULL, XVID_GBL_INIT, &xvid_gbl_init, NULL);
+        return 0;
+      }
+    EOS
+    system ENV.cc, "test.cpp", "-L#{lib}", "-lxvidcore", "-o", "test"
+    system "./test"
+  end
 end