Remove MachOObjectFile::getObject.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178986 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unused argument.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178987 91177308-0d34-0410-b5e6-96231b3b80d8
Construct MachOObject in MachOObjectFile's constructor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178988 91177308-0d34-0410-b5e6-96231b3b80d8