Define NONAMELESS{STRUCT,UNION} explicitly in the files that need them.

dlls/comctl32/comctl32undoc.c

diff --git a/dlls/comctl32/comctl32undoc.c b/dlls/comctl32/comctl32undoc.c
index e882aae..71308ac 100644
--- a/dlls/comctl32/comctl32undoc.c
+++ b/dlls/comctl32/comctl32undoc.c
@@ -37,6 +37,8 @@
 #include <ctype.h>
 #include <limits.h>
 
+#define NONAMELESSUNION
+#define NONAMELESSSTRUCT
 #include "commctrl.h"
 #include "objbase.h"
 #include "winbase.h"

dlls/comctl32/propsheet.c

diff --git a/dlls/comctl32/propsheet.c b/dlls/comctl32/propsheet.c
index d1d759d..8389fe5 100644
--- a/dlls/comctl32/propsheet.c
+++ b/dlls/comctl32/propsheet.c
@@ -25,6 +25,8 @@
 
 #include <string.h>
 
+#define NONAMELESSUNION
+#define NONAMELESSSTRUCT
 #include "winbase.h"
 #include "commctrl.h"
 #include "prsht.h"

dlls/comctl32/treeview.c

diff --git a/dlls/comctl32/treeview.c b/dlls/comctl32/treeview.c
index 1a79e13..faedd28 100644
--- a/dlls/comctl32/treeview.c
+++ b/dlls/comctl32/treeview.c
@@ -47,6 +47,8 @@
 #include <limits.h>
 #include <stdlib.h>
 
+#define NONAMELESSUNION
+#define NONAMELESSSTRUCT
 #include "winbase.h"
 #include "wingdi.h"
 #include "commctrl.h"