Simplify the parsing of unnamed globals. No functionality changed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210120 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a small bug in the parsing of anonymous globals.

It was able to parse

hidden dllexport global i32 42

but not

dllexport global i32 42

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210121 91177308-0d34-0410-b5e6-96231b3b80d8
Update comments to match reality.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210125 91177308-0d34-0410-b5e6-96231b3b80d8