lib_enc/ivas_stereo_eclvq_enc.c: Should include stl.h instead of basop32.h

The file lib_enc/ivas_stereo_eclvq_enc.c includes basop32.h:

/* used only for norm_s in the code_length_from_count function */
#include "basop32.h"

It should include stl.h, which then includes basop32.h