This moves the GLSL and ARB specific reserved constants out of directx.c into
the get_caps methods of the shader backends. That way the number of reserved
constants remains in the backend.

GL_LIMITS({v/p}shader_constantsF) now contains the real number of constants as
advertised by GL instead of some mixture of GL info and backend implementation
specifics. This makes it easier for backends to decide how many constants to
use.

DrawPrimitive now accepts the number of vertices, not the number of
primitives. This code was forgotten in the patch that changed this.
We're drawing triangles, so we are drawing num_primitives * 3 vertices.

In most cases we're fine with the vbo and glMapBuffer and never use the actual
heap memory copy. Try to stick to just the vbo copy and avoid allocating the
extra heap memory. In case it is needed(emulation or vertex conversion), fall
back to the old double buffering mode.

wined3d: Split vshader_program_add_param() in shader_arb_add_src_param() and shader_arb_add_dst_param().

WineD3D buffer FVFs will go away soon.