Get version and date as function for late execution. Provide default version

and date to be used while fetching the submodule isn't complete.

Author: balthisar

Package.swift

@@ -6,13 +6,17 @@ import PackageDescription
 
 
 // Get the values we need to populate the LIBTIDY_VERSION and RELEASE_DATE macros later.
-let PWD = (#filePath as NSString).deletingLastPathComponent
-let VERSION_FILE = NSString.path(withComponents: [PWD, "Sources", "CLibTidy", "version.txt"])
-var CONTENTS:[String]
-do {
-    CONTENTS = try String(contentsOfFile: VERSION_FILE).components(separatedBy: "\n")
+func tidyVersion() -> [String] {
+    let PWD = (#filePath as NSString).deletingLastPathComponent
+    let VERSION_FILE = NSString.path(withComponents: [PWD, "Sources", "CLibTidy", "version.txt"])
+    if let CONTENTS = try? String(contentsOfFile: VERSION_FILE).components(separatedBy: "\n") {
+        return CONTENTS
+    }
+
+    return ["5.0.0", "2021/01/01"]
 }
 
+
 let package = Package(
     name: "SwLibTidy",
     products: [
@@ -52,8 +56,8 @@ let package = Package(
             , sources: ["src"]
             , publicHeadersPath: "include"
             , cSettings: [
-                .define("LIBTIDY_VERSION", to: "\"\(CONTENTS[0])\"", nil),
-                .define("RELEASE_DATE", to: "\"\(CONTENTS[1])\"", nil)
+                .define("LIBTIDY_VERSION", to: "\"\(tidyVersion()[0])\"", nil),
+                .define("RELEASE_DATE", to: "\"\(tidyVersion()[1])\"", nil)
             ]
         ),