[KT-43276] Add watchos_x64 target

kotlin-native/shared/src/main/kotlin/org/jetbrains/kotlin/konan/target/ClangArgs.kt

@@ -104,7 +104,8 @@ class ClangArgs(private val configurables: Configurables) : Configurables by con
                 KonanTarget.WATCHOS_X86 ->
                     listOf("-stdlib=libc++", "-arch", "i386", "-isysroot", absoluteTargetSysRoot, "-mwatchos-simulator-version-min=$osVersionMin")
 
-                KonanTarget.WATCHOS_X64 -> TODO("implement me")
+                KonanTarget.WATCHOS_X64 ->
+                    listOf("-stdlib=libc++", "-isysroot", absoluteTargetSysRoot, "-mwatchos-simulator-version-min=$osVersionMin")
 
                 KonanTarget.ANDROID_ARM32, KonanTarget.ANDROID_ARM64,
                 KonanTarget.ANDROID_X86, KonanTarget.ANDROID_X64 -> {

kotlin-native/shared/src/main/kotlin/org/jetbrains/kotlin/konan/target/Platform.kt

@@ -34,7 +34,7 @@ class PlatformManager(private val distribution: Distribution, experimental: Bool
 
     constructor(konanHome: String, experimental: Boolean = false): this(Distribution(konanHome), experimental)
 
-    private val loaders = filteredOutEnabledButNotSupported.map {
+    private val loaders = enabled.map {
         it to loadConfigurables(it, distribution.properties, DependencyProcessor.defaultDependenciesRoot.absolutePath)
     }.toMap()
 
@@ -46,11 +46,5 @@ class PlatformManager(private val distribution: Distribution, experimental: Bool
     val hostPlatform = platforms.getValue(host)
 
     fun loader(target: KonanTarget) = loaders.getValue(target)
-
-    /**
-     * TODO: Don't forget to delete this field and replace all its usages to `enabled`.
-     */
-    val filteredOutEnabledButNotSupported
-        get() = enabled.filterNot { it == KonanTarget.WATCHOS_X64 }
 }