Removing the VIM browse patch.

The general reasoning is that the vim browse patch is very invasive,
has a high level of complexity, and is incompatible with a significant
number of other patches and it complicates further maintenance.

Additionally the patch has its own scrollback mechanism which seemingly
did not work properly - and nobody seems to have complained about this
since the patch was added back in May 2021.

If you want to try out the vim browse patch then I would recommend having
a play around with the patch author's own build that has this patch
integrated:
   - https://github.com/juliusHuelsmann/st-history-vim
   - https://github.com/juliusHuelsmann/st

Alternatively a tag has been added to this repository that refers to the
last commit that still has the vim browse patch:
   - https://github.com/bakkeby/st-flexipatch/tree/VIM_BROWSE_PATCH

win.h

@@ -21,9 +21,7 @@ enum win_mode {
 	MODE_NUMLOCK     = 1 << 17,
 	MODE_MOUSE       = MODE_MOUSEBTN|MODE_MOUSEMOTION|MODE_MOUSEX10\
 	                  |MODE_MOUSEMANY,
-	#if VIM_BROWSE_PATCH
-	MODE_NORMAL      = 1 << 18,
-	#endif // VIM_BROWSE_PATCH
+	MODE_PLACEHOLDER = 1 << 18,
 	#if KEYBOARDSELECT_PATCH
 	MODE_KBDSELECT   = 1 << 19,
 	#endif // KEYBOARDSELECT_PATCH