title: Compile Glew git code with MinGW on Windows
body: <p>When looking on glew project page there's a git repository with the latest code. </p>
  
  <p>Cloning the repository I saw that I need to download the extensions. The Makefile has a target called <em>extensions</em> that do the job of downloading everything from the internet.</p>
  
  <p>The problem is that this Makefile is default for Unix systems. When I tried to build glew on Windows, using <em>msysgit</em> and <em>mingw</em> I get the following error:</p>
  
  <pre><code>mingw32-make.exe extensions
  mingw32-make -C auto
  mingw32-make[1]: Entering directory `glew/auto'
  
  --------------------------------------------------------------------
  Creating descriptors
  --------------------------------------------------------------------
  rm -rf extensions/gl
  bin/update_ext.sh extensions/gl registry/gl blacklist
  Integer overflow in hexadecimal number at bin/parse_spec.pl line 337.
  Hexadecimal number &gt; 0xffffffff non-portable at bin/parse_spec.pl line 337.
  Integer overflow in hexadecimal number at bin/parse_spec.pl line 337.
  Hexadecimal number &gt; 0xffffffff non-portable at bin/parse_spec.pl line 337.
  Integer overflow in hexadecimal number at bin/parse_spec.pl line 337.
  Hexadecimal number &gt; 0xffffffff non-portable at bin/parse_spec.pl line 337.
  Integer overflow in hexadecimal number at bin/parse_spec.pl line 337.
  Hexadecimal number &gt; 0xffffffff non-portable at bin/parse_spec.pl line 337.
  Integer overflow in hexadecimal number at bin/parse_spec.pl line 337.
  Hexadecimal number &gt; 0xffffffff non-portable at bin/parse_spec.pl line 337.
  bin/filter_gl_ext.sh     extensions/gl
  Can't do inplace edit on extensions/gl/GL_HP_occlusion_test: Permission denied.
  Can't open extensions/gl/GL_HP_occlusion_test: No such file or directory.
  Can't do inplace edit on extensions/gl/GL_ARB_vertex_buffer_object: Permission d
  enied.
  Can't do inplace edit on extensions/gl/GL_ARB_vertex_shader: Permission denied.
  Can't open extensions/gl/GL_ARB_vertex_shader: No such file or directory.
  Can't open extensions/gl/GL_ARB_vertex_shader: No such file or directory.
  Can't open extensions/gl/GL_ARB_vertex_shader: No such file or directory.
  grep: extensions/gl/GL_ARB_vertex_shader: No such file or directory
  mingw32-make[1]: *** [extensions/gl/.dummy] Error 2
  mingw32-make[1]: Leaving directory `glew/auto'
  mingw32-make: *** [extensions] Error 2
  </code></pre>
  
  <p>I know this comes from <em>perl</em>, but how to solve it in Windows using MinGW and msysgit? 
  I first think about other environment setup like <em>cygwin</em> but I already have a setup that build a dozen of other projects using my current setup.</p>