starpufft: set detach to 0 to be able to call starpu_task_wait

starpufft/starpufftx1d.c

@@ -808,6 +808,7 @@ if (PARALLEL) {
 
 	/* Create FFT task */
 	task = starpu_task_create();
+	task->detach = 0;
 	task->cl = &STARPUFFT(fft_1d_codelet);
 	task->handles[0] = in;
 	task->handles[1] = out;

starpufft/starpufftx2d.c

@@ -806,6 +806,7 @@ if (PARALLEL) {
 
 	/* Create FFT task */
 	task = starpu_task_create();
+	task->detach = 0;
 	task->cl = &STARPUFFT(fft_2d_codelet);
 	task->handles[0] = in;
 	task->handles[1] = out;