fltmgr.sys: Add FltUnregisterFilter stub.

Signed-off-by: Alistair Leslie-Hughes <leslie_alistair@hotmail.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/fltmgr.sys/fltmgr.sys.spec

@@ -158,6 +158,6 @@
 @ stub FltUninitializeFileLock
 @ stub FltUninitializeOplock
 @ stub FltUnloadFilter
-@ stub FltUnregisterFilter
+@ stdcall FltUnregisterFilter(ptr)
 @ stub FltUntagFile
 @ stub FltWriteFile

dlls/fltmgr.sys/main.c

@@ -59,3 +59,8 @@ NTSTATUS WINAPI FltStartFiltering( PFLT_FILTER filter )
 
     return STATUS_SUCCESS;
 }
+
+void WINAPI FltUnregisterFilter( PFLT_FILTER filter )
+{
+    FIXME( "(%p): stub\n", filter );
+}