[NORMATIVE]Allow non-identical sequence headers
[NORMATIVE]Allow non-identical sequence headers

This commit changes the reference code to allow additional sequence
headers with different number of trailing 0 bits.

Change-Id: Icbb1c9a834b438271456fcda9323a3212dd62784

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