title: Cannot find Python.h when configuring pycairo 1.10.0
body: <p>I am trying to setup pycairo in <code>virtualenv</code> but setup fails when searching for Python.h header file</p>
  
  <pre><code>(draw)[root@collabdraw pycairo]# python ./waf configure --prefix=/usr
    ./options()
  Setting top to                           : /root/pycairo 
  Setting out to                           : /root/pycairo/build_directory 
    ./configure()
  Checking for 'gcc' (c compiler)          : /usr/bin/gcc 
  Checking for program python              : /root/virtualenvt/draw/bin/python 
  Checking for python version              : (3, 2, 0, 'final', 0) 
  Checking for library python3.2 in LIBDIR : not found 
  Checking for library python3.2 in python_LIBPL : not found 
  Checking for library python3.2 in $prefix/libs : not found 
  Checking for library python32 in LIBDIR        : not found 
  Checking for library python32 in python_LIBPL  : not found 
  Checking for library python32 in $prefix/libs  : not found 
  Checking for program /root/virtualenvt/draw/bin/python-config,python3.2-config,python-   config-3.2,python3.2m-config : /root/virtualenvt/draw/bin/python3.2-config 
  Checking for header Python.h                                                                                       : :-( 
  Asking python-config for the flags (pyembed)                                                                       : yes 
  Getting pyembed flags from python-config                                                                           : yes 
  Asking python-config for the flags (pyext)                                                                         : yes 
  Getting pyext flags from python-config                                                                             : Could not build python extensions 
  The configuration failed
  (complete log in /root/pycairo/build_directory/config.log)
  </code></pre>
  
  <p>Any ideas why <code>python ./waf configure --prefix=/usr</code> cannot find <code>Python.h</code>?  This file is located in virtaulenv directory</p>
  
  <pre><code>(draw)[root@collabdraw pycairo]# ls ~/virtualenvt/draw/include/python3.2m/Python.
  Python.h  ##### This is the file
  </code></pre>