Decoder: Setting BINAURAL_SPLIT_{CODED,PCM} without a head tracking trajectory results in a crash

Omitting a renderer configuration file for split rendering results in a default configuration being initialised. If the head rotation trajectory file argument is also omitted, the decoder crashes.

./IVAS_cod -mc 5_1 512000 48 scripts/testv/stv51MC48c.wav bit
./IVAS_dec -T scripts/trajectories/full_circle_in_15s.csv BINAURAL_SPLIT_CODED 48 bit split.bit 
vs
./IVAS_dec BINAURAL_SPLIT_CODED 48 bit split.bit 

IVAS_DEC_FeedHeadTrackData failed: Unexpected NULL pointer

Decoding finished prematurely: Unexpected NULL pointer

The crash occurs in decoder.c:2349 after attempting to call IVAS_DEC_FeedHeadTrackData().