Include _FoundationCollections for CMake build

Author: cthielen

Sources/FoundationEssentials/NotificationCenter/AsyncMessage+AsyncSequence.swift

@@ -15,6 +15,8 @@ internal import _ForSwiftFoundation
 internal import CollectionsInternal
 #elseif canImport(DequeModule)
 internal import DequeModule
+#elseif canImport(_FoundationCollections)
+internal import _FoundationCollections
 #endif
 #if canImport(os)
 internal import os.log