read_sequence_header_obu should return 0 on error.
read_sequence_header_obu should return 0 on error.

read_sequence_header_obu returns a byte count. It should not return an
error code on failure because the error code (a positive integer) would
be misinterpreted as a byte count. Instead, save the error code in
pbi->common.error.error_code and return 0.

Change-Id: I91a34cbfbcbb4ebfcbbc21f320aaeb24e7968e84

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