Mark the declarations as extern "C" in case we're included by a C++ application.
Mark the declarations as extern "C" in case we're included by a C++
application.

Fixes issue #36


binarycrusader/libproxy,markcox/libproxy,horar/libproxy,markcox/libproxy,markcox/libproxy,libproxy/libproxy,binarycrusader/libproxy,maxinbjohn/libproxy,anonymous2ch/libproxy,libproxy/libproxy,libproxy/libproxy,horar/libproxy,horar/libproxy,libproxy/libproxy,anonymous2ch/libproxy,cicku/libproxy,markcox/libproxy,cicku/libproxy,horar/libproxy,anonymous2ch/libproxy,codegooglecom/libproxy,markcox/libproxy,anonymous2ch/libproxy,anonymous2ch/libproxy,libproxy/libproxy,maxinbjohn/libproxy,horar/libproxy,maxinbjohn/libproxy,codegooglecom/libproxy,anonymous2ch/libproxy,binarycrusader/libproxy,cicku/libproxy,cicku/libproxy,anonymous2ch/libproxy,maxinbjohn/libproxy,libproxy/libproxy,maxinbjohn/libproxy,horar/libproxy,maxinbjohn/libproxy,codegooglecom/libproxy,binarycrusader/libproxy,markcox/libproxy,libproxy/libproxy,codegooglecom/libproxy,horar/libproxy,binarycrusader/libproxy,binarycrusader/libproxy,markcox/libproxy,codegooglecom/libproxy,codegooglecom/libproxy,markcox/libproxy,maxinbjohn/libproxy,cicku/libproxy,binarycrusader/libproxy,binarycrusader/libproxy,cicku/libproxy,cicku/libproxy,codegooglecom/libproxy