use max args in all places that need it

Assignment2/main.c

@@ -85,7 +85,7 @@ void exec() {
     print_prompt("Please input exec subcommand:\n");
 
     char *buffer = calloc(100, sizeof(char)); // input buffer size 100
-    char **subcommand = calloc(6, sizeof(char *)); //size 6 to allow for 5 arguments and a null pointer
+    char **subcommand = calloc(MAX_ARGS, sizeof(char *)); //size 6 to allow for 5 arguments and a null pointer
     for (int i = 0; i < MAX_ARGS; i++) {
         subcommand[i] = NULL;     //make sure each pointer is a null pointer
     }