[PECOFF][Driver] Remove quotes from command line arguments.

The command line option in .drectve section may be quoted by double
quotes, and if that's the case we have to remove them.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@187390 91177308-0d34-0410-b5e6-96231b3b80d8