Use the range variant of find instead of unpacking begin/end

If the result of the find is only used to compare against end(), just
use is_contained instead.

No functionality change is intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278433 91177308-0d34-0410-b5e6-96231b3b80d8
78 files changed