XAACachePlanarMonoStippleWeak to XAAGetCachePlanarMonoStipple() for
consistency with other parts of xaa and fix forward declaration in
xaalocal.h. Fixes last comments on Bug #962.
framebuffer formats except cfb and the overlay modes should work, and
r128 and radeon need to be loaded from the ati driver (both issues to
be fixed soon). Tested on i740, s3virge, mach64, tdfx, vesa, and vga
drivers. elfloader users shouldn't be affected.