Stop trying to analyze class-hierarchies for dependently-scoped id-expressions;

Stop trying to analyze class-hierarchies for dependently-scoped id-expressions;
there's nothing interesting we can say now that we're correctly not requiring
the qualifier to name a known base class in dependent contexts.

Require scope specifiers on member access expressions to name complete types
if they're not dependent;  delay lookup when they are dependent.

Use more appropriate diagnostics when qualified implicit member access
expressions find declarations from unrelated classes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@90289 91177308-0d34-0410-b5e6-96231b3b80d8