Update to 1.4.1
    
    - New upstream release 1.4.1
      - Build error with gcrypt backend
      - Always do "forced" window updates to avoid corner case stalls
      - aes: the init function fails when OpenSSL has AES support
      - transport_send: finish in-progress key exchange before sending data
      - channel_write: acknowledge transport errors
      - examples/x11.c: make sure sizeof passed to read operation is correct
      - examples/x11.c: fix suspicious sizeof usage
      - sftp_packet_add: verify the packet before accepting it
      - SFTP: preserve the original error code more
      - sftp_packet_read: adjust window size as necessary
      - Use safer snprintf rather then sprintf in several places
      - Define and use LIBSSH2_INVALID_SOCKET instead of INVALID_SOCKET
      - sftp_write: cannot return acked data *and* EAGAIN
      - sftp_read: avoid data *and* EAGAIN
      - libssh2.h: add missing prototype for libssh2_session_banner_set()
    - Drop upstream patches now included in release tarball