Log Message:
Updated curl to 7.50.1.

 Bugfixes:

    TLS: switch off SSL session id when client cert is used
    TLS: only reuse connections with the same client cert
    curl_multi_cleanup: clear connection pointer for easy handles
    include the CURLINFO_HTTP_VERSION man page into the release tarball
    include the http2-server.pl script in the release tarball
    test558: fix test by stripping file paths from FD lines
    spnego: Corrected miss-placed * in Curl_auth_spnego_cleanup() declaration
    tests: Fix for http/2 feature
    cmake: Fix for schannel support
    curl.h: make public types void * again
    win32: fix a potential memory leak in Curl_load_library
    travis: fix OSX build by re-installing libtool
    mbedtls: Fix debug function name