ValueEnumerator: Use std::find_if, NFC

Mehdi's pattern recognition pulled this one out.  This is cleaner with
std::find_if than with the strange helper function that took an iterator
by reference and updated it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267271 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed