hpeldsp: Add half-pel functions (currently copies of dsputil)
vp3: Use hpeldsp instead of dsputil for half-pel functions

This makes vp3 independent of dsputil.
vp56: Use hpeldsp instead of dsputil for half-pel functions

This makes vp5 and vp6 independent of dsputil.
indeo3: Use hpeldsp instead of dsputil for half-pel functions

This makes the Indeo 3 decoder independent of dsputil.
bink: Use hpeldsp instead of dsputil for half-pel functions
interplayvideo: Use hpeldsp instead of dsputil for half-pel functions

This makes interplayvideo independent of dsputil.
mimic: Use hpeldsp instead of dsputil for half-pel functions
svq1: Use hpeldsp instead of dsputil for half-pel functions

This makes svq1 independent of dsputil.
mpegvideo: Use hpeldsp instead of dsputil for half-pel functions

This also converts vc1, since that is mpegvideo-based.
svq3: Use hpeldsp instead of dsputil for half-pel functions
svq1enc: Use hpeldsp instead of dsputil for half-pel functions
mjpeg: Use hpeldsp instead of dsputil for half-pel functions
x86: hpeldsp: Move half-pel assembly from dsputil to hpeldsp
ppc: hpeldsp: Move half-pel assembly from dsputil to hpeldsp
arm: hpeldsp: Move half-pel assembly from dsputil to hpeldsp
bfin: hpeldsp: Move half-pel assembly from dsputil to hpeldsp
sh4: hpeldsp: Move half-pel assembly from dsputil to hpeldsp
sparc: hpeldsp: Move vis half-pel assembly from dsputil to hpeldsp
alpha: hpeldsp: Move half-pel assembly from dsputil to hpeldsp
dsputil: Remove hpel functions (moved to hpeldsp)