[ASTImporter] Fix import of NestedNameSpecifierLoc.

Summary:
Import type location in case of TypeSpec and TypeSpecWithTemplate.
Without this fix the imported NespedNameSpecifierLoc will have an
invalid begin location.

Reviewers: a.sidorin, shafik, a_sidorin, martong

Reviewed By: a_sidorin

Subscribers: rnkovacs, jdoerfert, dkrupp, martong, Szelethus, gamesh411, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D55358

llvm-svn: 356151