advpack: Constify some variables

[Andrew Talbot]

Changelog:
    advpack: Constify some variables.

diff --git a/dlls/advpack/files.c b/dlls/advpack/files.c
index 5003239..5e9ce30 100644
--- a/dlls/advpack/files.c
+++ b/dlls/advpack/files.c
@@ -996,8 +996,8 @@ HRESULT WINAPI GetVersionFromFileExW(LPCWSTR lpszFilename, LPDWORD pdwMSVer,
     BOOL bFileCopied = FALSE;
     UINT uValueLen;
 
-    static WCHAR backslash[] = {'\\',0};
-    static WCHAR translation[] = {
+    static const WCHAR backslash[] = {'\\',0};
+    static const WCHAR translation[] = {
         '\\','V','a','r','F','i','l','e','I','n','f','o',
         '\\','T','r','a','n','s','l','a','t','i','o','n',0
     };