shell32: Constify some variables

[Andrew Talbot]

Changelog:
    shell32: Constify some variables.

diff --git a/dlls/shell32/shfldr.h b/dlls/shell32/shfldr.h
index 4950254..56f81dd 100644
--- a/dlls/shell32/shfldr.h
+++ b/dlls/shell32/shfldr.h
@@ -70,7 +70,7 @@ static inline int SHELL32_GUIDToStringW (REFGUID guid, LPWSTR str)
 }
 
 void SHELL_FS_ProcessDisplayFilename(LPWSTR szPath, DWORD dwFlags);
-BOOL SHELL_FS_HideExtension(LPWSTR pwszPath);
+BOOL SHELL_FS_HideExtension(LPCWSTR pwszPath);
 
 DEFINE_GUID( CLSID_UnixFolder, 0xcc702eb2, 0x7dc5, 0x11d9, 0xc6, 0x87, 0x00, 0x04, 0x23, 0x8a, 0x01, 0xcd );
 DEFINE_GUID( CLSID_UnixDosFolder, 0x9d20aae8, 0x0625, 0x44b0, 0x9c, 0xa7, 0x71, 0x88, 0x9c, 0x22, 0x54, 0xd9 );
diff --git a/dlls/shell32/shfldr_fs.c b/dlls/shell32/shfldr_fs.c
index 0fa690d..0cc08b5 100644
--- a/dlls/shell32/shfldr_fs.c
+++ b/dlls/shell32/shfldr_fs.c
@@ -712,7 +712,7 @@ static const WCHAR NeverShowExtW[] = { 'N','e','v','e','r','S','h','o','w','E',
  *  TRUE, if the filename's extension should be hidden
  *  FALSE, otherwise.
  */
-BOOL SHELL_FS_HideExtension(LPWSTR szPath)
+BOOL SHELL_FS_HideExtension(LPCWSTR szPath)
 {
     HKEY hKey;
     DWORD dwData;
@@ -1170,7 +1170,7 @@ ISFHelper_fnAddFolder (ISFHelper * iface, HWND hwnd, LPCWSTR pwszName,
  * Builds a list of paths like the one used in SHFileOperation from a table of
  * PIDLs relative to the given base folder
  */
-static WCHAR *build_paths_list(LPCWSTR wszBasePath, int cidl, LPCITEMIDLIST *pidls)
+static WCHAR *build_paths_list(LPCWSTR wszBasePath, int cidl, const LPCITEMIDLIST *pidls)
 {
     WCHAR *wszPathsList;
     WCHAR *wszListPos;