zero out execute_in to reveal a bug.

There is a bug in c2r new array execution.
I am not sure how to fix it; apparently
line 953 of api-basic.c:
```
complex_conjugate(conj_in, conj_out, ths->rnk_n, ths->local_ni);
```
overwrites the input of with the conjugate of the output.
This is not shown if the test case does not zeros execute_in before running the c2r.

I will fire another issue for the bug.