Correct tag names for RECTL and SCROLLINFO structs.

diff --git a/include/winuser.h b/include/winuser.h
index 534807d..a7e4c41 100644
--- a/include/winuser.h
+++ b/include/winuser.h
@@ -2109,7 +2109,7 @@
 #define SBM_GETSCROLLINFO      0x00ea
 
 /* Scrollbar info */
-typedef struct
+typedef struct tagSCROLLINFO
 {
     UINT    cbSize;
     UINT    fMask;