Continue the work started by Dragos' Makefile patch (LLVMLibsOptions usage)
Continue the work started by Dragos' Makefile patch (LLVMLibsOptions usage)

Also replace hard-coded paths with a variable.
Fixed a comment.
Included missing dependencies on Mac OS X (lldbPluginDynamicLoaderPOSIX.a
is a common dependency).
We can't use EXPORTED_SYMBOL_FILE on Darwin right now, don't pass it to
the linker just yet.



git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@157618 91177308-0d34-0410-b5e6-96231b3b80d8

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