Low bit-depth encoding fails due to the check in riceStatReset

[tsukuba.takeshi]

As in the adopted text in JVET-W0178, the StatCoeff[idx] is initialized as below:

• If sps_persistent_rice_adaptation_enabled_flag is equal to 0, the values of StatCoeff[ idx ] for idx ranging from 0 to 2, inclusive, are initialized to be equal to 0.
• Otherwise the following applies: StatCoeff[ idx ] = ( 2 * Floor( Log2( bitDepth − 10 ) ) (X)

But in the the riceStatReset function, the initialization takes care of only the latter case (sps_persistent_rice_adaptation_enabled_flag==1). As a result, the following check in the riceStatReset prevents anyone from using 8/10 bit coding regardless of using high bit-depth or not.

  CHECK(bitDepth <= 10,"BitDepth shall be larger than 10.");

A fix is to align SW with Spec. i.e.

• Add an initialization process for the case of sps_persistent_rice_adaptation_enabled_flag == 0 in riceStatReset.

Discussion is found in:
​https://vcgit.hhi.fraunhofer.de/jvet/VVCSoftware_VTM/-/merge_requests/2098#note_15804

[tsukuba.takeshi]

MR is ​https://vcgit.hhi.fraunhofer.de/jvet/VVCSoftware_VTM/-/merge_requests/2108

[ksuehring]

Fixed as suggested