BuildSystem/Windows: * Added 5.1.50 (GA) MySQL client sources for crosscompiling (or lazy) windows people.
* Added an option to autosearch for your own installed MySQL as before. Note that default setting is to use the internal MySQL.
* You can now build 32-bit even if your MySQL is x64 and vice versa.
* Recommended MySQL server version for use with provided MySQL client sources is 5.1.x.
* If your server version is different, let CMake autofind and use it instead (check EXTERNAL_MYSQL option)

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branch : trunk