Create FileStream with File.Create when writing signature file from fsc

Author: vzarytovskii

src/fsharp/fsc.fs

@@ -359,7 +359,7 @@ module InterfaceFileWriter =
             if tcConfig.printSignatureFile="" then
                 Console.Out
             else
-                new StreamWriter(FileSystem.FileStreamReadWriteShim(tcConfig.printSignatureFile), Encoding.UTF8) :> TextWriter
+                new StreamWriter(FileSystem.FileStreamCreateShim(tcConfig.printSignatureFile), Encoding.UTF8) :> TextWriter
 
         if tcConfig.printSignatureFile <> "" && not (List.exists (FileSystemUtils.checkSuffix tcConfig.printSignatureFile) FSharpLightSyntaxFileSuffixes) then
             fprintfn os "#light"