[ScopedNoAliasAA] Remove an unneccesary set

We are trying to prove that one group of operands is a subset of
another.  We did this by populating two Sets and determining that every
element within one was inside the other.

However, this is unnecessary.  We can simply construct a single set and
test if each operand is within it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278641 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed