Remove a number of unnecessary dsputil.h #includes
x86: dsputil: Eliminate some unnecessary dsputil_x86.h #includes
ppc: Drop a bunch of unnecessary dsputil_altivec.h #includes
x86: Drop some unnecessary YASM ifdefs

Dead code elimination is enough to avoid undefined references in these cases.
x86: h264_qpel: Simplify an #if conditional

The extra conditions are covered by previous #ifs and conditional compilation.
x86: dsputil: Move ff_apply_window_int16_* bits to ac3dsp, where they belong
dsputil: Move DV-specific ff_zigzag248_direct table to dvdata