extended the multi-thread explanation

Updated: April 11, 2005 (http://curl.haxx.se/docs/faq.html)

Updated: April 13, 2005 (http://curl.haxx.se/docs/faq.html)

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  programs. libcurl will use thread-safe functions instead of non-safe ones if

  your system has such.

  We would appreciate some kind of report or README file from those who have

  used libcurl in a threaded environment.

  If you use a OpenSSL-powered libcurl in a multi-threaded environment, you

  need to provide one or two locking functions:

    http://www.openssl.org/docs/crypto/threads.html#DESCRIPTION

  If you use a GnuTLS-powered libcurl in a multi-threaded environment, you

  need to provide locking function(s) for libgcrypt (which is used by GnuTLS

  for the crypto functions).

    [informative link missing]

  5.2 How can I receive all data into a large memory chunk?