WL#5030: Split and remove mysql_priv.h

- Extract "basic" typedefs into a separate header file

- Create header file for components missing those

- Move extern declaration of global variables to the correct component

- Try to find out structure of file to extract into separate files.

Move all declarations of global variables into their associated components.

Move all function declarations into the header file of the associated components.

Move all inline functions into the header file of the associated component.

Move all macros into the header file of the associated component.

Eliminate all #include.

Eliminate all circular include dependencies.

Add header files where necessary to ensure that the system compiles.