LALInspiralRingdownWave.c: fix bugs introduced by complex number conversion

- real part is used to calculate imaginary part, so must calculate each
  separately before assigning to complex number
- refs #1169

(cherry picked from commit c3e4ff6ab3108e8c9a04fdb0da0cafebc494e14a)
LALPSpinInspiralRingdownWave.c: fix bugs introduced by complex number conversion

- real part is used to calculate imaginary part, so must calculate each
  separately before assigning to complex number
- refs #1170

(cherry picked from commit 3e3390925e4f19dea5ddc2eff28d3547d4142c1e)