This routine clears a bit in a byte string. 'bit_number' must
be an integer bit number ranging from 1 to 32767 with each bit
being numbered in ascending order from right to left.
byte_string byte or array of bytes to clear (up to 4096 bytes)
bit_number bit number (starts at 1)
This function requires the following include files:
setbit(_c), tstbit(_c), bit_field_circular_shift_c, icshft,
int bit_number = BIT_NUMBER;