Remove project int types: Case int_u: Replace with uint32_t.

- Replace int_u with uint32_t (same size, should give no problems).
  In fact, only usage found seems to be dead code (some functions in
  ui.h seem not to be used anymore).
- Remove int_u typedef.

Requested in #459.

src/types.h

@@ -15,6 +15,5 @@
  * already defined, so we use char_u to avoid trouble.
  */
 typedef unsigned char char_u;
-typedef unsigned int int_u;
 
 #endif /* NEOVIM_TYPES_H */

src/ui.h

@@ -21,7 +21,7 @@ int clip_isautosel_plus(void);
 void clip_modeless(int button, int is_click, int is_drag);
 void clip_start_selection(int col, int row, int repeated_click);
 void clip_process_selection(int button, int col, int row,
-                            int_u repeated_click);
+                            uint32_t repeated_click);
 void clip_may_redraw_selection(int row, int col, int len);
 void clip_clear_selection(VimClipboard *cbd);
 void clip_may_clear_selection(int row1, int row2);