AMDGPU: Fix failure to select branch with optnone

opt-bisect/optnone disable the AMDGPUUniformAnnotateValues pass.
The heuristic in the custom selector for brcond deferred the
branch uniformity check to the pattern, which would fail.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315360 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed