Get rid of variable function argument

Author: SebastianOsinski

SQLite/Extensions/FTS4.swift

@@ -28,7 +28,9 @@ extension Module {
         return FTS4([column] + more)
     }
 
-    @warn_unused_result public static func FTS4(var columns: [Expressible] = [], tokenize tokenizer: Tokenizer? = nil) -> Module {
+    @warn_unused_result public static func FTS4(columns: [Expressible] = [], tokenize tokenizer: Tokenizer? = nil) -> Module {
+        var columns = columns
+        
         if let tokenizer = tokenizer {
             columns.append("=".join([Expression<Void>(literal: "tokenize"), Expression<Void>(literal: tokenizer.description)]))
         }