[ModuloSchedule] Do target loop analysis before peeling.

    Simple change to call target hook analyzeLoopForPipelining before
    changing the loop. After peeling analyzing the loop may be more
    complicated for target that don't have a loop instruction. This doesn't
    affect Hexagone and PPC as they have hardware loop instructions.

    Differential Revision: https://reviews.llvm.org/D69912