SPAR inter-frame vs. intra-frame memory

It seems that SBA SPAR modules memory usage is not always consistent and a review would result in maximum memory saving.

In particular, there are buffers which are defined as static and allocated in a inter-frame heap memory while these buffers could be defined locally in respective functions and allocated in a stack (or eventually in an intra-frame heap memory).

E.g. hSpar->hMdEnc->cov_real[][] and hSpar->hMdEnc->cov_dtx_real[][] could be defined in the function ivas_spar_enc_process(). Or hMdEnc->mixer_mat_local could be defined in the function ivas_spar_md_enc_process(). Etc.

These buffers should be identified and used locally in a stack.