add UT for cavlc_b not support case
add UT for cavlc_b not support case

ruil2/openh264,shihuade/openh264,GuangweiWang/openh264,ruil2/openh264,cisco/openh264,ruil2/openh264,shihuade/openh264,mstorsjo/openh264,GuangweiWang/openh264,GuangweiWang/openh264,ruil2/openh264,mstorsjo/openh264,cisco/openh264,GuangweiWang/openh264,mstorsjo/openh264,shihuade/openh264,mstorsjo/openh264,GuangweiWang/openh264,GuangweiWang/openh264,cisco/openh264,mstorsjo/openh264,shihuade/openh264,cisco/openh264,shihuade/openh264,mstorsjo/openh264,ruil2/openh264,ruil2/openh264,GuangweiWang/openh264,cisco/openh264,cisco/openh264,shihuade/openh264,cisco/openh264,mstorsjo/openh264,shihuade/openh264,ruil2/openh264