advapi32: Constify some variables

[Andrew Talbot]

Changelog:
    advapi32: Constify some variables.

diff --git a/dlls/advapi32/security.c b/dlls/advapi32/security.c
index 2338aca..aa7f336 100644
--- a/dlls/advapi32/security.c
+++ b/dlls/advapi32/security.c
@@ -2764,7 +2764,7 @@ static BOOL match_account( ULONG idx, const LSA_UNICODE_STRING *account )
 /*
  * Helper function for LookupAccountNameW
  */
-BOOL lookup_local_wellknown_name( LSA_UNICODE_STRING *account_and_domain,
+BOOL lookup_local_wellknown_name( const LSA_UNICODE_STRING *account_and_domain,
                                   PSID Sid, LPDWORD cbSid,
                                   LPWSTR ReferencedDomainName,
                                   LPDWORD cchReferencedDomainName,
@@ -2827,7 +2827,7 @@ BOOL lookup_local_wellknown_name( LSA_UNICODE_STRING *account_and_domain,
     return ret;
 }
 
-BOOL lookup_local_user_name( LSA_UNICODE_STRING *account_and_domain,
+BOOL lookup_local_user_name( const LSA_UNICODE_STRING *account_and_domain,
                              PSID Sid, LPDWORD cbSid,
                              LPWSTR ReferencedDomainName,
                              LPDWORD cchReferencedDomainName,