DO CONCURRENT: compiler flags to enable parallelization

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What is the probability that cons<=0?

The pattern is deterministic, so I could add an early exit clause:

! Initialize v_new
            v_max = large_negative
            ap_ind = 0
            ! Choose a' optimally by stepping through all possible values
            do ap_c=1,n_a
                aprime_val = ap_grid(ap_c)
                cons = R*a_val + z_val - aprime_val
                if (cons>0.0d0) then
                    v_temp = f_util(cons) + beta*EV(ap_c,z_c)
                    !v_temp = f_util(cons) + beta*sum(v(ap_c,:)*z_tran(z_c,:))
                    if (v_temp>v_max) then
                        v_max = v_temp
                        ap_ind = ap_c
                    end if
                else
                    exit
                endif
            enddo !end a'

I did not do it in the initial version because I read somewhere that introducing exit clauses within nested loops can be bad for performance. Of course the exit clauses saves on the number of iterations on the ap_c loop: it may prevent some optimizations however so the net effect on performance is not clear a priori.