Merge pull request #10003 from felipepiovezan/felipe/fix_swiftless_builds

[lldb] Conditionally add the swift OS plugin directory

Author: felipepiovezan

lldb/source/Plugins/OperatingSystem/CMakeLists.txt

@@ -1,4 +1,6 @@
 if (LLDB_ENABLE_PYTHON)
   add_subdirectory(Python)
-  add_subdirectory(SwiftTasks)
+  if (LLDB_ENABLE_SWIFT_SUPPORT)
+    add_subdirectory(SwiftTasks)
+  endif()
 endif()