Enable imaginary absorbing boundaries on GPUs

Description

Implement the local potential kernel for complex potentials for all spin cases and use it in the right place.

News

Enable imaginary absorbing boundaries on GPUs

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.

share/opencl/cl_complex.h

@@ -23,6 +23,14 @@
 
 #include <cl_global.h>
 
+inline double2 complex_number(const double x, const double y){
+#ifdef CUDA
+  return double2(x, y);
+#else
+    return (double2) (x, y);
+#endif
+}
+
 inline double2 complex_conj(const double2 a){
 #ifdef CUDA
   return double2(a.x, -a.y);