msi: Replace const pointer parameters with correct pointers to const

[Andrew Talbot]

Changelog:
    msi: Replace const pointer parameters with correct pointers to const.

diff -urN a/dlls/msi/custom.c b/dlls/msi/custom.c
--- a/dlls/msi/custom.c	2007-02-26 17:43:07.000000000 +0000
+++ b/dlls/msi/custom.c	2007-03-05 18:41:37.000000000 +0000
@@ -457,7 +457,7 @@
     return rc;
 }
 
-static msi_custom_action_info *find_action_by_guid( const LPGUID guid )
+static msi_custom_action_info *find_action_by_guid( const GUID *guid )
 {
     msi_custom_action_info *info;
     BOOL found = FALSE;
@@ -481,7 +481,7 @@
     return info;
 }
 
-static DWORD WINAPI ACTION_CallDllFunction( const LPGUID guid )
+static DWORD WINAPI ACTION_CallDllFunction( const GUID *guid )
 {
     msi_custom_action_info *info;
     MsiCustomActionEntryPoint fn;