[PECOFF][Writer] Templatize connectAtomsWithLayoutEdge()

Templatize connectAtomsWithLayoutEdge() so that it can handle other types of
defined atoms.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@185125 91177308-0d34-0410-b5e6-96231b3b80d8
[PECOFF][Writer] Use a constant instead of a magic number.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@185128 91177308-0d34-0410-b5e6-96231b3b80d8