Merge pull request #2898 from uberhacker/add-pngcheck-package

Add pngcheck package

packages/pngcheck.rb

+require 'package'
+
+class Pngcheck < Package
+  description 'pngcheck verifies the integrity of PNG, JNG and MNG files'
+  homepage 'http://www.libpng.org/pub/png/apps/pngcheck.html'
+  version '2.3.0'
+  source_url 'https://prdownloads.sourceforge.net/project/png-mng/pngcheck/2.3.0/pngcheck-2.3.0.tar.gz'
+  source_sha256 '77f0a039ac64df55fbd06af6f872fdbad4f639d009bbb5cd5cbe4db25690f35f'
+
+  binary_url ({
+  })
+  binary_sha256 ({
+  })
+
+  def self.build
+    system "gcc -O -DUSE_ZLIB -I#{CREW_PREFIX}/include -o pngcheck pngcheck.c -L#{CREW_LIB_PREFIX} -lz"
+  end
+
+  def self.install
+    system "install -Dm755 pngcheck #{CREW_DEST_PREFIX}/bin/pngcheck"
+  end
+end