[PECOFF] Emit PE+ idata tables.

Import tables in the PE+ format is an array of 64 bit numbers,
although the executable size is still limited to 4GB in PE+.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@216039 91177308-0d34-0410-b5e6-96231b3b80d8