[analyzer] RetainCount: A function isn't a CFRetain if it takes no arguments.

[analyzer] RetainCount: A function isn't a CFRetain if it takes no arguments.

Don't crash when a function has a name that starts with "CF" and ends with
"Retain" but takes 0 arguments. In particular, don't try to treat it as if
it returns its first argument.

These problems are inevitable because the checker is naming-convention-based,
but at least we shouldn't crash.

Differential Revision: https://reviews.llvm.org/D59123

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@356223 91177308-0d34-0410-b5e6-96231b3b80d8