clang-format: Add new option to indent wrapped function declarations.

Though not completely identical, make former
IndentFunctionDeclarationAfterType change this flag for backwards
compatibility (it is somewhat close in meaning and better the err'ing on
an unknown config flag).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@212597 91177308-0d34-0410-b5e6-96231b3b80d8