uint32_t options -> File::OpenOptions options

Summary:
This patch re-types everywhere that passes a File::OpenOptions
as a uint32_t so it actually uses File::OpenOptions.

It also converts some OpenOptions related functions that fail
by returning 0 or NULL into llvm::Expected

split off from https://reviews.llvm.org/D68737

Reviewers: JDevlieghere, jasonmolenda, labath

Reviewed By: labath

Subscribers: lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D68853

llvm-svn: 374817