ARM: assembly optimized nearest scaled 'src_8888_8888'

ARM: assembly optimized nearest scaled 'src_8888_8888'

Benchmark on ARM Cortex-A8 r1p3 @500MHz, 32-bit LPDDR @166MHz:
 Microbenchmark (scaling 2000x2000 image with scale factor close to 1x):
  before: op=1, src=20028888, dst=20028888, speed=44.36 MPix/s
  after:  op=1, src=20028888, dst=20028888, speed=39.79 MPix/s

Benchmark on ARM Cortex-A8 r2p2 @1GHz, 32-bit LPDDR @200MHz:
 Microbenchmark (scaling 2000x2000 image with scale factor close to 1x):
  before: op=1, src=20028888, dst=20028888, speed=102.36 MPix/s
  after:  op=1, src=20028888, dst=20028888, speed=163.12 MPix/s