Update heapsort.c

[yogirajbshinde21]

1. Defined a maximum heap size using a constant.

2. Used a separate function for heapify.

3. Simplified the main loop.

4. Removed unnecessary comments.

5. Used more descriptive variable names.

6. Used more meaningful output messages.

I am creating a pull request for...

• [ ] New algorithm
• [x] Update to an algorithm
• [ ] Fix an error
• [ ] Other - Describe below