Removed the 'stdbool' header file and updated code

I realized we were barred using any other standard library so I removed the one I added.

Author: nanafox

2-selection_sort.c

@@ -10,23 +10,23 @@
 void selection_sort(int *array, size_t size)
 {
 size_t i, j, cur_min;
-bool min_found; /* tracks whether a lesser value is found */
+int min_found; /* tracks whether a lesser value is found */
 
 /* there's no need to perform sorting on empty or one-element arrays */
-if (size == 0 || size == 1)
+if (array == NULL || size < 2)
 return;
 
 for (i = 0; i < size - 1; i++)
 {
 cur_min = i;
-min_found = false;
+min_found = 0;
 
 for (j = i + 1; j < size; j++)
 {
 if (array[j] < array[cur_min])
 {
 cur_min = j;
-min_found = true;
+min_found = 1;
 }
 }
 

sort.h

@@ -3,7 +3,6 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <stdbool.h>
 
 /**
  * struct listint_s - Doubly linked list node