title: Error in porting opencv library to pepper_31
body: <p>I want to build <code>opencv</code> library for <code>pepper_31</code> for ARM architecture, but when I am building library with command</p>
  
  <p><code>sudo NACL_ARCH=arm make opencv</code></p>
  
  <p>below <strong>error</strong> is coming</p>
  
  <pre><code>build_tools/naclports.py build ports/opencv
  Building 'zlib-1.2.8' [arm]
  Building 'libpng-1.6.8' [arm]
  Building 'jpeg-6b' [arm]
  naclports: opencv-2.4.7: disabled for current arch: arm.
  make: *** [opencv] Error 1
  </code></pre>
  
  <p>When I am building library for <code>pnacl</code> with command</p>
  
  <p><code>sudo NACL_ARCH=pnacl make opencv</code></p>
  
  <p>below <strong>error</strong> is coming</p>
  
  <pre><code>Wrote script /home/saurav/nacl_sdk/naclports/src/out/repository/zlib-1.2.8/minigzip
  ./minigzip: line 8: /home/saurav/nacl_sdk/pepper_31/tools/sel_ldr_x86_64: cannot execute binary file
  ./minigzip: line 8: /home/saurav/nacl_sdk/pepper_31/tools/sel_ldr_x86_64: cannot execute binary file
    *** minigzip test FAILED ***
  naclports: Building 'zlib-1.2.8' failed.
  make: *** [opencv] Error 1
  </code></pre>
  
  <p>Can any one please suggest how to do it for ARM architecture?</p>