lib_dec differs a lot between ivas-main and ivas-float-update

Basic info

in !2521, Lib_dec.c is very different between ivas-main and ivas-float-update. Many differences are cometic, but the ones below need a more careful review by someone having more knowledge about that file. @vaclav feel free to reassigned if needed.

Bug description

• at around Ln103 (ivas-float-update), in IVAS_DEC struct, flushbuffer should be defined as a void /* instead of Word16/* both in basop and ivas-float-update
• at around line 1533 (ivas-float-update), in function IVAS_DEC_SetEditableParameters() this code is missing in basop and ivas-float-update:

if ( hIvasDec == NULL || hIvasDec->st_ivas == NULL )
{
    return IVAS_ERR_UNEXPECTED_NULL_POINTER;
}

• in function getOutputBufferSize(), around Ln 2553 of ivas-float-update, different use of MAX_OUTPUT_CHANNELS vs RENDERER_MAX_OUTPUT_CHANNELS and MAX_NUM_OBJECTS vs IVAS_MAX_NUM_OBJECTS ( basop follows ivas-float-update, might need an update if defines are not equivalent)
• IVAS_DEC_is_split_rendering_enabled() and IVAS_DEC_is_split_rendering_coded_out() should return ivas_error, not word16 (both basop and ivas-float-update need to be corrected)
• code related to RTP_S4_251135_CR26253_0016_REV1 is missing in basop and ivas-float-update
• handles and comments need review as well (but that's cosmetic)

@kiene , @pihlajakuja for awareness

Ways to reproduce