clang-format: Be more conservative about column layout formatting.

Specifically, if a braced list has at least one nested braced list,
format it either all on one line or in one column (i.e. one item per
line).

This seems in general to be an improvement as the structure of nested
braced lists can make a tightly packed outer braced list hard to read.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@193345 91177308-0d34-0410-b5e6-96231b3b80d8
Tooling/ReplacementsYaml.h: Prune Tooling's llvm::yaml::ScalarTraits<std::string> corresponding to LLVM r193344.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@193346 91177308-0d34-0410-b5e6-96231b3b80d8
Replaced duplicate code with calls to forwardInfo.

Also made move constructor handling safer.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@193347 91177308-0d34-0410-b5e6-96231b3b80d8