Target: compute the swiftReflection target more generically
Target: compute the swiftReflection target more generically

We did not compute the swiftReflection target sufficiently generically.  This
manifested as a problem when cross-compiling lldb for Windows.  We would try to
link against swiftReflection rather than swiftReflection-windows-x86_64.  Yank
the architecture mapping function from the corelibs SwiftSupport and use that to
generically map for non-Darwin targets.

apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb