[ModuloSchedule] removeBranch() *before* creating the trip count condition

The Hexagon code assumes there's no existing terminator when inserting its
trip count condition check.

This causes swp-stages5.ll to break. The generated code looks good to me,
it is likely a permutation. I have disabled the new codegen path to keep
everything green and will investigate along with the other 3-4 tests
that have different codegen.

Fixes expensive-checks build.

llvm-svn: 373629