Change typeIncompatible to return an AttrBuilder instead of new-ing an AttributeSet.

Change typeIncompatible to return an AttrBuilder instead of new-ing an AttributeSet.

This makes use of the new API which can remove attributes from a set given a builder.

This is much faster than creating a temporary set and reduces llc time by about 0.3% which was all spent creating temporary attributes sets on the context.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236668 91177308-0d34-0410-b5e6-96231b3b80d8