Consistently put {} onto the same line for empty functions.

This fixes llvm.org/PR15167.

Before:
LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL()
    : AAAAAAAA(10), BBBBBBBBB(10) {
}
LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL() : AAAAAAAA(10) {}

After:
LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL()
    : AAAAAAAA(10), BBBBBBBBB(10) {}
LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL() : AAAAAAAA(10) {}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175800 91177308-0d34-0410-b5e6-96231b3b80d8