riched20: Add spare area to ITextServicesImpl to work around broken apps.

dlls/riched20/txtsrv.c

diff --git a/dlls/riched20/txtsrv.c b/dlls/riched20/txtsrv.c
index 95d6f7c..d4679f7 100644
--- a/dlls/riched20/txtsrv.c
+++ b/dlls/riched20/txtsrv.c
@@ -57,6 +57,7 @@
    ITextHost *pMyHost;
    LONG ref;
    CRITICAL_SECTION csTxtSrv;
+   char spare[256];
 } ITextServicesImpl;
 
 static const ITextServicesVtbl textservices_Vtbl;