Moved undocshell.h to dlls/shell32. Removed shell16.h.

diff --git a/dlls/shell32/shellole.c b/dlls/shell32/shellole.c
index 132ce38..70f10c2 100644
--- a/dlls/shell32/shellole.c
+++ b/dlls/shell32/shellole.c
@@ -17,7 +17,7 @@
 #include "winreg.h"
 #include "winerror.h"
 
-#include "wine/undocshell.h"
+#include "undocshell.h"
 #include "wine/unicode.h"
 #include "shell32_main.h"