PR16715: Fix assert in verifier: only mark call to 'operator new' as 'builtin' if
corresponding 'operator new' was actually emitted as a function marked 'nobuiltin'.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187374 91177308-0d34-0410-b5e6-96231b3b80d8