secur32: Cast-qual warning fix

[Andrew Talbot]

Changelog:
    secur32: Cast-qual warning fix.

diff -urN a/dlls/secur32/util.c b/dlls/secur32/util.c
--- a/dlls/secur32/util.c	2006-11-09 17:45:24.000000000 +0000
+++ b/dlls/secur32/util.c	2006-11-13 19:43:02.000000000 +0000
@@ -151,7 +151,7 @@
 
     MD5Init(&ctx);
     MD5Update(&ctx, session_key, 16);
-    MD5Update(&ctx, (unsigned char*)magic, lstrlenA(magic)+1);
+    MD5Update(&ctx, (const unsigned char*)magic, lstrlenA(magic)+1);
     MD5Final(&ctx);
     memcpy(subkey, ctx.digest, 16);
 }