argvC: fix off-by-one error.

Python/pywarpx/_libwarpx.py

@@ -399,10 +399,15 @@ def get_nattr_species(self, species_name):
     def amrex_init(self, argv, mpi_comm=None):
         # --- Construct the ctype list of strings to pass in
         argc = len(argv)
-        argvC = (_LP_c_char * (argc+1))()
+        argvC = (_LP_c_char * argc)()
+        print("amrex_init argv=", argv)
+        print("amrex_init len(argv)=", len(argv))
         for i, arg in enumerate(argv):
             enc_arg = arg.encode('utf-8')
             argvC[i] = ctypes.create_string_buffer(enc_arg)
+        print("len(argvC)=", len(argvC))
+        print("argc=", argc)
+        print("argvC=", argvC)
 
         if mpi_comm is None or MPI is None:
             self.libwarpx_so.amrex_init(argc, argvC)