[manifest] Ignore CMake files (apple#47)

The package manager doesn’t like it when it finds unexpected non-source files in source directories.

Author: lorentey

Package.swift

@@ -67,6 +67,7 @@ let package = Package(
         "OrderedCollections",
       ],
       path: "Sources/Collections",
+      exclude: ["CMakeLists.txt"],
       swiftSettings: settings),
 
     // Testing support module
@@ -109,6 +110,7 @@ let package = Package(
     // Deque<Element>
     .target(
       name: "DequeModule",
+      exclude: ["CMakeLists.txt"],
       swiftSettings: settings),
     .testTarget(
       name: "DequeTests",
@@ -118,6 +120,7 @@ let package = Package(
     // OrderedSet<Element>, OrderedDictionary<Key, Value>
     .target(
       name: "OrderedCollections",
+      exclude: ["CMakeLists.txt"],
       swiftSettings: settings),
     .testTarget(
       name: "OrderedCollectionsTests",