[analyzer] Re-enable cplusplus.NewDelete (but not NewDeleteLeaks).

As mentioned in the previous commit message, the use-after-free and
double-free warnings for 'delete' are worth enabling even while the
leak warnings still have false positives.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178891 91177308-0d34-0410-b5e6-96231b3b80d8
11 files changed