Fix: Push then push-pop sequence bug

[mo-atef-dev]

The current library has a bug that causes the header and tail indicators to overreach into the next buffer. This happens when a nonempty buffer repeatedly receives a sequence of push-pop operations. Each push operation increases the tail and each pop operation increases the head, both without limit.

Here is an exact code to reproduce the problem (assuming a buffer capacity of 4 bytes):

// Assume buffer size is 4 bytes

circularBuffer_t* b = circular_buffer_init(sizeof(uint8_t));
uint8_t dataIn = 0xAA;
uint8_t dataOut = 0;

circular_buffer_push(b, &dataIn);

circular_buffer_push(b, &dataIn);
circular_buffer_pop(b, &dataOut);

circular_buffer_push(b, &dataIn);
circular_buffer_pop(b, &dataOut);

circular_buffer_push(b, &dataIn);
circular_buffer_pop(b, &dataOut);

circular_buffer_push(b, &dataIn);
circular_buffer_pop(b, &dataOut);

circular_buffer_push(b, &dataIn);
circular_buffer_pop(b, &dataOut);

After the above operations (or any number of more push-pop pair of operations), a debugger can be used to inspect that the tail and head indicators have surpassed the maximum index (in this case 3 since the size is 4) of the data array in the circular buffer structure.