ClangMoveTests.cpp: Appease msc18.

  clang-tools-extra\unittests\clang-move\ClangMoveTests.cpp(216) : error C2593: 'operator =' is ambiguous
          llvm\include\llvm/ADT/SmallVector.h(898): could be 'const llvm::SmallVector<std::string,4> &llvm::SmallVector<std::string,4>::operator =(std::initializer_list<std::basic_string<char,std::char_traits<char>,std::allocator<char>>>)'
          llvm\include\llvm/ADT/SmallVector.h(893): or       'const llvm::SmallVector<std::string,4> &llvm::SmallVector<std::string,4>::operator =(llvm::SmallVectorImpl<T> &&)'
          with
          [
              T=std::string
          ]
          llvm\include\llvm/ADT/SmallVector.h(883): or       'const llvm::SmallVector<std::string,4> &llvm::SmallVector<std::string,4>::operator =(llvm::SmallVector<std::string,4> &&)'
          llvm\include\llvm/ADT/SmallVector.h(873): or       'const llvm::SmallVector<std::string,4> &llvm::SmallVector<std::string,4>::operator =(const llvm::SmallVector<std::string,4> &)'
          while trying to match the argument list '(llvm::SmallVector<std::string,4>, initializer-list)'

llvm-svn: 284360