fix mpi complex dtype

apparently some mpi implementations don't do mpi_c_float_complex. so I'm
using mpi_complex, even though they claim I shouldn't use fortran
stuff...

src/fluid_solver.cpp

@@ -421,7 +421,7 @@ FLUID_SOLVER_DEFINITIONS(
         float,
         fftwf_complex,
         MPI_FLOAT,
-        MPI_C_FLOAT_COMPLEX)
+        MPI_COMPLEX)
 //FLUID_SOLVER_DEFINITIONS(
 //        FFTW_MANGLE_DOUBLE,
 //        double,

src/fluid_solver_base.cpp

@@ -20,7 +20,7 @@
 
 
 
-//#define NDEBUG
+#define NDEBUG
 
 #include <cassert>
 #include <cmath>
@@ -451,7 +451,7 @@ FLUID_SOLVER_BASE_DEFINITIONS(
         float,
         fftwf_complex,
         MPI_FLOAT,
-        MPI_C_FLOAT_COMPLEX)
+        MPI_COMPLEX)
 //FLUID_SOLVER_BASE_DEFINITIONS(
 //        FFTW_MANGLE_DOUBLE,
 //        double,