[ASTImporter] Import ctor initializers after setting flags.

Summary:
Code to import "ctor initializers" at import of functions
is moved to be after the flags in the newly created function
are imported. This fixes an error when the already created but
incomplete (flags are not set) function declaration is accessed.

Reviewers: martong, shafik, a_sidorin, a.sidorin

Reviewed By: shafik

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

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65935

llvm-svn: 369098