common_unittest: modify the NALREADER_TEST
common_unittest: modify the NALREADER_TEST

Modify the NALREADER_TEST ReadAsUnits and ReadAsWhole to make them compatible
with new NalReader behaviors.

Signed-off-by: wudping <eada3ae4a96a673269eca90300aaefadacf3db15@intel.com>

YuJiankang/libyami,lizhong1008/libyami,01org/libyami,lizhong1008/libyami,stripes416/libyami,lizhong1008/libyami,01org/libyami,stripes416/libyami,YuJiankang/libyami,YuJiankang/libyami,stripes416/libyami,01org/libyami