[PECOFF] Support /manifestuac:NO.

If the value for /manifestuac is "NO", LLD will create a manifest XM
file but won't emit <trustinfo> element.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@206633 91177308-0d34-0410-b5e6-96231b3b80d8