AOM_QM: modify low QM levels.
AOM_QM: modify low QM levels.

Use a more aggressive tail to simulate larger viewing
distances better for low value QM levels.

This does not change default QM coding (qmlevel >= 5)
or non-QM coding.

Change-Id: Ifb6fa6faf8ce9b77177c97798e08418788c53fbd

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom