iter/thresh.h: change bool to _Bool
struct operator_p_s;
extern const struct operator_p_s* prox_thresh_create(unsigned int D, const long dim[__VLA(D)], const float lambda, const unsigned long flags, _Bool gpu);
-extern const struct operator_p_s* prox_niht_thresh_create(unsigned int D, const long dim[D], const unsigned int k, const unsigned long flags, bool gpu);
+extern const struct operator_p_s* prox_niht_thresh_create(unsigned int D, const long dim[D], const unsigned int k, const unsigned long flags, _Bool gpu);
extern void thresh_free(const struct operator_p_s* data);
