Spin trace of Dirac propagator

Syntax	void QLA_M_eqop_spintrace_P( restrict QLA_ColorMatrix *r,
	QLA_DiracPropagator *a)
Meaning	$r_{i_c,j_c} = \sum_{i_s} a_{i_c,i_s,j_c,i_s}$
eqop	eq