[test] Add InputGraph tests

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@195388 91177308-0d34-0410-b5e6-96231b3b80d8
Fix indentation and whitespace.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@195389 91177308-0d34-0410-b5e6-96231b3b80d8
Fix file header comment.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@195393 91177308-0d34-0410-b5e6-96231b3b80d8