[PECOFF][Writer] Amend the comment about DLL linking.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@185307 91177308-0d34-0410-b5e6-96231b3b80d8
[PECOFF][Writer] Do not emit the empty section as Windows loader rejects such executable.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@185308 91177308-0d34-0410-b5e6-96231b3b80d8
[PECOFF][Writer] Add setter methods that sets the import address table location to file header.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@185309 91177308-0d34-0410-b5e6-96231b3b80d8