[lldb] Fill Watch/AppleTV simulator gaps in PlatformDarwin

[teemperor]

Summary

When running the test suite against the Watch/AppleTV simulator we currently hitting
the unimplemented parts of PlatformDarwin for the respective simulator platforms.

This just adds the respective switch cases.

This whole code path depends on having a valid Target, so can't just unittest this code
without refactoring it. So instead this is tested by just running the testsuite against
the respective simulators (which is how I found this).

[aprantl]

This trivially LGTM, but we should think about moving this into XcodeSDK.

lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp

case XcodeSDK::Type::MacOSX:
     sdks_spec.AppendPathComponent("MacOSX.platform");
     break;
   case XcodeSDK::Type::iPhoneSimulator:
     sdks_spec.AppendPathComponent("iPhoneSimulator.platform");
     break;
   case XcodeSDK::Type::iPhoneOS:
     sdks_spec.AppendPathComponent("iPhoneOS.platform");
     break;
+  case XcodeSDK::Type::WatchSimulator:
+    sdks_spec.AppendPathComponent("WatchSimulator.platform");
+    break;
+  case XcodeSDK::Type::AppleTVSimulator:
+    sdks_spec.AppendPathComponent("AppleTVSimulator.platform");
+    break;
   default:
     llvm_unreachable("unsupported sdk");
   }
 
   sdks_spec.AppendPathComponent("Developer");
   sdks_spec.AppendPathComponent("SDKs");
 
   if (sdk_type == XcodeSDK::Type::MacOSX) {
if (!version.empty()) {
     case XcodeSDK::Type::iPhoneSimulator:
       minimum_version_option.PutCString("-mios-simulator-version-min=");
       minimum_version_option.PutCString(version.getAsString());
       break;
     case XcodeSDK::Type::MacOSX:
       minimum_version_option.PutCString("-mmacosx-version-min=");
       minimum_version_option.PutCString(version.getAsString());
       break;
+    case XcodeSDK::Type::WatchSimulator:
+      minimum_version_option.PutCString("-mwatchos-simulator-version-min=");
+      minimum_version_option.PutCString(version.getAsString());
+      break;
+    case XcodeSDK::Type::AppleTVSimulator:
+      minimum_version_option.PutCString("-mtvos-version-min=");
+      minimum_version_option.PutCString(version.getAsString());
+      break;
     default:
       llvm_unreachable("unsupported sdk");
     }
     options.push_back(std::string(minimum_version_option.GetString()));
   }
 
   FileSpec sysroot_spec;
   // Scope for mutex locker below