[PECOFF] Add a test for /noentry.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198074 91177308-0d34-0410-b5e6-96231b3b80d8
[PECOFF] Add file extensions to temporary files.

No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@198075 91177308-0d34-0410-b5e6-96231b3b80d8