[CMake] Gate 'dsymutil' dependency
[CMake] Gate 'dsymutil' dependency

Only add `dsymutil` as a test dependency when this is not a stand-alone
build (LLDB_BUILT_STANDALONE).

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@330568 91177308-0d34-0410-b5e6-96231b3b80d8

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