fixes visual studio error Change-Id: I86206f17ca951b15e247c1b92561847d8c21ec7a
Move class VpxScaleBase to new file test/vpx_scale_test.h. Add new file test/vp9_scale_test.cc with ScaleFrameTest. BUG=webm:1419 Change-Id: Iec2098eafcef99b94047de525e5da47bcab519c1