[mach-o] fix DEBUG_WITH_TYPE to compile without warnings in non-debug case

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@194171 91177308-0d34-0410-b5e6-96231b3b80d8
[mach-o] add llvm_unreachable

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@194172 91177308-0d34-0410-b5e6-96231b3b80d8
[mach-o] fix EXPECT_EQ types

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@194173 91177308-0d34-0410-b5e6-96231b3b80d8