Add include of stdarg.h to host_varfn_function.c
#include <stdio.h>
#include <omp.h>
#include <hostrpc.h>
-
+#include <stdarg.h>
// This user variable function returns a uint so declare function
// as hostrpc_varfn_uint_t .
hostrpc_varfn_uint_t my3argfn;
