INSTALL: Updated MSVC 6 caveats

   MSVC 6 caveats

   --------------

   If you use MSVC 6 it is required that you use the February 2003 edition PSDK:

   http://www.microsoft.com/msdownload/platformsdk/sdkupdate/psdk-full.htm

   If you use MSVC 6 it is required that you use the February 2003 edition of

   the 'Platform SDK' which can be downloaded from:

   http://www.microsoft.com/en-us/download/details.aspx?id=12261

   Building any software with MSVC 6 without having PSDK installed is just

   asking for trouble down the road once you have released it, you might notice

   choice of static vs dynamic runtime and third party libraries. Anyone using

   software built in such way will at some point regret having done so.

   When someone uses MSVC 6 without PSDK he is using a compiler back from 1998.

   If the compiler has been updated with the installation of a service pack as

   those mentioned in http://support.microsoft.com/kb/194022 the compiler can be

   safely used to read source code, translate and make it object code.

   header files and libraries with bugs and security issues which have already

   been addressed and fixed long time ago.

   In order to make use of the updated system headers and fixed libraries

   for MSVC 6, it is required that 'Platform SDK', PSDK from now onwards,

   is installed. The specific PSDK that must be installed for MSVC 6 is the

   February 2003 edition, which is the latest one supporting the MSVC 6 compiler,

   this PSDK is also known as 'Windows Server 2003 PSDK' and can be downloaded

   from http://www.microsoft.com/msdownload/platformsdk/sdkupdate/psdk-full.htm

   So, building curl and libcurl with MSVC 6 without PSDK is absolutely

   discouraged for the benefit of anyone using software built in such

   environment. And it will not be supported in any way, as we could just