Fixed a potential crash if a metadata category we write into doesn't already exist.
Fixed a potential crash if a metadata category
we write into doesn't already exist.

<rdar://problem/11775508>


git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@159700 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb