msvcrt/tests: Load __mb_cur_max and _mbctype dynamically since they may not be available to link against.

That bug was uncovered by Henri's change of the bitfield sizes.

It makes the code more readable and will help us to merge the ALPHAOP
and COLOROP code.

Fix the unnecessary SUBLANG_NATURAL.
Change the font size from 8 to 9.

This moves setting baseShader.hex_version and baseShader.functionLength to
shader_get_registers_used(), where it's more appropriate.