COFF: Add constants for optional data directory.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186377 91177308-0d34-0410-b5e6-96231b3b80d8
Add a version of sys::fs::status that uses fstat.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186378 91177308-0d34-0410-b5e6-96231b3b80d8
[Object/COFF] Add import_directory_table_entry.

Summary: Add import_directory_table_entry to use for .idata section.

Reviewers: Bigcheese

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1059

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186379 91177308-0d34-0410-b5e6-96231b3b80d8
Remember that we have a null terminated string.

This is a micro optimization. Instead of going char*->StringRef->Twine->char*,
go char*->Twine->char* and avoid having to copy the filename on the stack.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186380 91177308-0d34-0410-b5e6-96231b3b80d8
Use open+fstat instead of stat+open.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186381 91177308-0d34-0410-b5e6-96231b3b80d8