Remove the deleted RISC OS files.

src/gui_riscos.h

-/* vi:set ts=8 sts=4 sw=4:
- *
- * VIM - Vi IMproved	by Bram Moolenaar
- *
- * Do ":help uganda"  in Vim to read copying and usage conditions.
- * Do ":help credits" in Vim to see a list of people who contributed.
- */
-
-#define FEAT_BROWSE
-
-#define TASK 0x4b534154
-
-/* Nested wimp flags: */
-#define CHILD_FIX_TO_WORKAREA	0
-#define CHILD_FIX_TO_LEFT	1
-#define CHILD_FIX_TO_BOTTOM	1
-#define CHILD_FIX_TO_RIGHT	2
-#define CHILD_FIX_TO_TOP	2
-
-#define CHILD_SELF_SCROLL	0
-#define CHILD_PARENT_SCROLL	1
-
-#define CHILD_LEFT		16
-#define CHILD_BOTTOM		18
-#define CHILD_RIGHT		20
-#define CHILD_TOP		22
-#define CHILD_SCROLL_X		24
-#define CHILD_SCROLL_Y		26
-
-int wimp_poll(int mask, int *block);
-int wimp_poll_idle(int mask, int *block, int end_time);
-void ro_open_main(int *block);