Remove BitcodeReader::setBufferOwned.

We do have use cases for the bitcode reader owning the buffer or not, but we
always know which one we have when we construct it.

It might be possible to simplify this further, but this is a step in the
right direction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211205 91177308-0d34-0410-b5e6-96231b3b80d8
Change IRObjectFile to parse the bitcode lazily.

The main point of this class is to provide a cheap object interface to a bitcode
file, so it has to be as lazy as possible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211207 91177308-0d34-0410-b5e6-96231b3b80d8
Make getBaseObject static.

Thanks to David Majnemer for noticing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211208 91177308-0d34-0410-b5e6-96231b3b80d8