Added missing WINAPI attribute to two forward declarations.

diff --git a/relay32/snoop.c b/relay32/snoop.c
index 704f547..271f3eb 100644
--- a/relay32/snoop.c
+++ b/relay32/snoop.c
@@ -24,8 +24,8 @@
 
 char **debug_snoop_excludelist = NULL, **debug_snoop_includelist = NULL;
 
-extern void SNOOP_Entry();
-extern void SNOOP_Return();
+extern void WINAPI SNOOP_Entry();
+extern void WINAPI SNOOP_Return();
 
 #ifdef __i386__