Changed every use of ASTImporter::Import to Import_New

Reviewers: a.sidorin, shafik, martong, a_sidorin

Reviewed By: a_sidorin

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

Tags: #clang

Differential Revision: https://reviews.llvm.org/D55049

llvm-svn: 357913