Remove the warning for variables declared in the if-expression being used in

Remove the warning for variables declared in the if-expression being used in
the else clause. The problem is that it's overly zealous and will respond to
uses in assignments, or after assignments. We should bring this back once we
can do it right. Fixes PR7100.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@110314 91177308-0d34-0410-b5e6-96231b3b80d8