mouse: Remove CHECK_DOUBLE_CLICK conditionals

This is now always defined.

src/nvim/mouse.c

@@ -169,11 +169,9 @@ retnomove:
     // (MOUSE_FOCUS was set above if we dragged first).
     if (dragwin == NULL || (flags & MOUSE_RELEASED))
       win_enter(wp, true);                      // can make wp invalid!
-# ifdef CHECK_DOUBLE_CLICK
     // set topline, to be able to check for double click ourselves
     if (curwin != old_curwin)
       set_mouse_topline(curwin);
-# endif
     if (on_status_line) {                       // In (or below) status line
       // Don't use start_arrow() if we're in the same window
       if (curwin == old_curwin)

src/nvim/term.c

@@ -2819,11 +2819,9 @@ static void switch_to_8bit(void)
   LOG_TR("Switching to 8 bit");
 }
 
-#ifdef CHECK_DOUBLE_CLICK
 static linenr_T orig_topline = 0;
 static int orig_topfill = 0;
-#endif
-#if defined(CHECK_DOUBLE_CLICK) || defined(PROTO)
+
 /*
  * Checking for double clicks ourselves.
  * "orig_topline" is used to avoid detecting a double-click when the window
@@ -2838,7 +2836,6 @@ void set_mouse_topline(win_T *wp)
   orig_topline = wp->w_topline;
   orig_topfill = wp->w_topfill;
 }
-#endif
 
 /*
  * Check if typebuf.tb_buf[] contains a terminal key code.
@@ -3529,7 +3526,6 @@ int check_termcode(int max_offset, char_u *buf, int bufsize, int *buflen)
           is_drag = TRUE;
         current_button = held_button;
       } else if (wheel_code == 0)   {
-# ifdef CHECK_DOUBLE_CLICK
         {
           static int orig_mouse_col = 0;
           static int orig_mouse_row = 0;
@@ -3563,9 +3559,6 @@ int check_termcode(int max_offset, char_u *buf, int bufsize, int *buflen)
           orig_topline = curwin->w_topline;
           orig_topfill = curwin->w_topfill;
         }
-# else
-        orig_num_clicks = NUM_MOUSE_CLICKS(mouse_code);
-# endif
         is_click = TRUE;
         orig_mouse_code = mouse_code;
       }

src/nvim/term.h

@@ -52,10 +52,6 @@
  * 128 = 16384 columns, now it's reduced to 10000. */
 #define MOUSE_COLOFF 10000
 
-#if defined(UNIX)
-# define CHECK_DOUBLE_CLICK 1  /* Checking for double clicks ourselves. */
-#endif
-
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "term.h.generated.h"
 #endif