Fix debug build

Reported by ghubcoder in #2, debug builds were broken due to
incorrect MAX_NARG macro - it should be COMM_MAX_NARG.

tcp_comm.c

 
 	unsigned int i;
 	for (i = 0; i < n_cmds; i++) {
-		assert(cmds[i]->nargs <= MAX_NARG);
-		assert(cmds[i]->resp_nargs <= MAX_NARG);
+		assert(cmds[i]->nargs <= COMM_MAX_NARG);
+		assert(cmds[i]->resp_nargs <= COMM_MAX_NARG);
 	}
 
 	ctx->cmds = cmds;