Fixed a small typo.

include/winuser.h

diff --git a/include/winuser.h b/include/winuser.h
index 7a5eb3a..eada590 100644
--- a/include/winuser.h
+++ b/include/winuser.h
@@ -1157,7 +1157,7 @@
 {
     UINT16  mkSize;
     BYTE    mkKeyList;
-    BYTE    szKeyPhrase[1];
+    BYTE    szKeyphrase[1];
 } MULTIKEYHELP, *LPMULTIKEYHELP;
 
 typedef struct {