Added a sanity check for the libcurl link-time version.
Added a sanity check for the libcurl link-time version.

ninemoreminutes/pycurl,jcharum/pycurl,m13253/pycurl-python3,jcharum/pycurl,jcharum/pycurl,m13253/pycurl-python3,ninemoreminutes/pycurl,m13253/pycurl-python3,ninemoreminutes/pycurl,ninemoreminutes/pycurl