In range-based for-loops, prefer splitting after ":".

Before:
for (const aaaaaaaaaaaaaaaaaaaaa &
         aaaaaaaaa : aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa) {}

After:
for (const aaaaaaaaaaaaaaaaaaaaa &aaaaaaaaa :
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa) {}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176087 91177308-0d34-0410-b5e6-96231b3b80d8