[LoopInterchange] Correcting the profitability check

Before D135808, There would be endless loop interchange posibility (no
proper priority was there in profitability check. Any profitable check
may leads to loop-interchange). With this patch, there  is no endless
interchange (priority in profitable check is defined. Order of decision
is 'Cache cost' check, 'InstrOrderCost', 'Vectorization'). Corrected the
dependency checking inside isProfitableForVectorization(), corrected the
checking of bad order loops in isProfitablePerInstrOrderCost().

Reviewed By: Meinersbur, bmahjour, #loopoptwg

Differential Revision: https://reviews.llvm.org/D135808