Fix bug in DynTypedMatcher::constructVariadic() that would cause false negatives.

Summary:
DynTypedMatcher::constructVariadic() where the restrict kind of the
different matchers are not related causes the matcher to have a "None"
restrict kind. This causes false negatives for anyOf and eachOf.
Change the logic to get a common ancestor if there is one.
Also added regression tests that fail without the fix.

Reviewers: klimek

Subscribers: klimek, cfe-commits

Differential Revision: http://reviews.llvm.org/D5580