64-bit cleanness: convert client requests to receive and return UWords.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@2921 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/memcheck/mac_shared.h b/memcheck/mac_shared.h
index 88deee5..922c34c 100644
--- a/memcheck/mac_shared.h
+++ b/memcheck/mac_shared.h
@@ -334,7 +334,7 @@
 extern void MAC_(common_fini)         ( void (*leak_check)(void) );
 
 extern Bool MAC_(handle_common_client_requests) ( ThreadId tid, 
-                                                  UInt* arg_block, UInt* ret );
+                                                  UWord* arg_block, UWord* ret );
 
 extern void MAC_(print_malloc_stats) ( void );