title: Error Installing M2Crypto in windows: poll.h file missing
body: <p>I am trying to build the M2Crpto-0.23 version.It throws the error :</p>
  
  <pre><code>**SWIG/_m2crypto_wrap.c:6377:18: error: poll.h: No such file or directory**
  SWIG/_m2crypto_wrap.c: In function 'ssl_sleep_with_timeout':
  SWIG/_m2crypto_wrap.c:6613: error: storage size of 'fd' isn't known
  SWIG/_m2crypto_wrap.c:6640: error: 'POLLIN' undeclared (first use in this      function)
  SWIG/_m2crypto_wrap.c:6640: error: (Each undeclared identifier is reported only once
  SWIG/_m2crypto_wrap.c:6640: error: for each function it appears in.)
  SWIG/_m2crypto_wrap.c:6645: error: 'POLLOUT' undeclared (first use in this function)
  SWIG/_m2crypto_wrap.c:6659: warning: implicit declaration of function 'poll'
  SWIG/_m2crypto_wrap.c:6613: warning: unused variable 'fd'
  SWIG/_m2crypto_wrap.c: In function 'x509v3_lhash':
  SWIG/_m2crypto_wrap.c:7209: warning: return from incompatible pointer type
  error: Setup script exited with error: command 'c:\\mingw\\bin\\gcc.exe'    failed with exit status 1
  </code></pre>
  
  <p>Can anyone help me on this?</p>