Set the vim auto-indent setting for open braces after case statements to

Set the vim auto-indent setting for open braces after case statements to
follow LLVM source convention.

Before:
  case X: {
            stuff;
          }

After:
  case X: {
    stuff;
  }

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93055 91177308-0d34-0410-b5e6-96231b3b80d8