Update cmake build setup so lldb doesn't link against the DebugSymbols framework on macOS, in line with the source/xcode project changes in r364243. <rdar://problem/49458356> 
Update cmake build setup so lldb doesn't link against the DebugSymbols
framework on macOS, in line with the source/xcode project changes in
r364243.
<rdar://problem/49458356> 


git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@364979 91177308-0d34-0410-b5e6-96231b3b80d8

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