Add directory writability checks for sudoedit.

src/sudo.h

@@ -128,6 +128,7 @@ struct user_details {
 #define CD_EXEC_BG		0x04000
 #define CD_SUDOEDIT_COPY	0x08000
 #define CD_SUDOEDIT_FOLLOW	0x10000
+#define CD_SUDOEDIT_CHECKDIR	0x20000
 
 struct preserved_fd {
     TAILQ_ENTRY(preserved_fd) entries;