Changes in CRC detection v3: - Changed get_dep and other functions called in it ...

Changes in CRC detection v3: - Changed get_dep and other functions called in it (names are changed to continue_to_check_dep_for_if, continue_to_check_dep_for_xor). To check whether xor statement is for crc calculation and whether if's condition is for checking MSB/LSB being 1, go up by def-chain until the loop boundaries. The continue_to_check_dep_for_xor function keeps phi_statements if they are from loop header (it may be crc's definition). Modified algorithms detects crc's phi statement in case of there is an if in if within the loop. The continue_to_check_dep_for_if besides checking whether the if is for checking MSB/LSB being one, also tries to determine which phi statement is for crc and which one for the data. - Added set_loop_statements_not_visited function to unset only statement of the loop (as only statements within the loop may be visited).

Addition in testsuit:
  - Added new crc test (crc-23.c).