refactor: collapse statements in single assignments

Problem:

Variables are often assigned multiple places in common patterns.

Solution:

Replace these common patterns with different patterns that reduce the
number of assignments.

Use `MAX` and `MIN`:
```c
if (x < y) {
  x = y;
}

// -->

x = MAX(x, y);
```

```c
if (x > y) {
  x = y;
}

// -->

x = MIN(x, y);
```

Use ternary:
```c
int a;
if (cond) {
  a = b;
} els {
  a = c;
}

// -->

int a = cond ? b : c;

```

1 files changed, 13 insertions, 38 deletions

diff --git a/src/nvim/move.c b/src/nvim/move.c
index 8c206b3e8d..6324466dcc 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -894,9 +894,7 @@ void curs_columns(win_T *wp, int may_scroll)
           new_leftcol = wp->w_leftcol + diff;
         }
       }
-      if (new_leftcol < 0) {
-        new_leftcol = 0;
-      }
+      new_leftcol = MAX(new_leftcol, 0);
       if (new_leftcol != (int)wp->w_leftcol) {
         wp->w_leftcol = new_leftcol;
         win_check_anchored_floats(wp);
@@ -969,11 +967,8 @@ void curs_columns(win_T *wp, int may_scroll)
       if (n > plines - wp->w_height_inner + 1) {
         n = plines - wp->w_height_inner + 1;
       }
-      if (n > 0) {
-        wp->w_skipcol = width1 + (n - 1) * width2;
-      } else {
-        wp->w_skipcol = 0;
-      }
+      wp->w_skipcol = n > 0 ? width1 + (n - 1) * width2
+                            : 0;
     } else if (extra == 1) {
       // less than 'scrolloff' lines above, decrease skipcol
       assert(so <= INT_MAX);
@@ -990,9 +985,7 @@ void curs_columns(win_T *wp, int may_scroll)
       while (endcol > wp->w_virtcol) {
         endcol -= width2;
       }
-      if (endcol > wp->w_skipcol) {
-        wp->w_skipcol = endcol;
-      }
+      wp->w_skipcol = MAX(wp->w_skipcol, endcol);
     }
 
     // adjust w_wrow for the changed w_skipcol
@@ -1129,9 +1122,7 @@ void f_screenpos(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
     semsg(_(e_invalid_line_number_nr), pos.lnum);
     return;
   }
-  if (pos.col < 0) {
-    pos.col = 0;
-  }
+  pos.col = MAX(pos.col, 0);
   int row = 0;
   int scol = 0;
   int ccol = 0;
@@ -1423,9 +1414,7 @@ bool scrolldown(win_T *wp, linenr_T line_count, int byfold)
     foldAdjustCursor(wp);
     coladvance(wp, wp->w_curswant);
   }
-  if (wp->w_cursor.lnum < wp->w_topline) {
-    wp->w_cursor.lnum = wp->w_topline;
-  }
+  wp->w_cursor.lnum = MAX(wp->w_cursor.lnum, wp->w_topline);
 
   return moved;
 }
@@ -1506,12 +1495,8 @@ bool scrollup(win_T *wp, linenr_T line_count, bool byfold)
     wp->w_botline += line_count;            // approximate w_botline
   }
 
-  if (wp->w_topline > wp->w_buffer->b_ml.ml_line_count) {
-    wp->w_topline = wp->w_buffer->b_ml.ml_line_count;
-  }
-  if (wp->w_botline > wp->w_buffer->b_ml.ml_line_count + 1) {
-    wp->w_botline = wp->w_buffer->b_ml.ml_line_count + 1;
-  }
+  wp->w_topline = MIN(wp->w_topline, wp->w_buffer->b_ml.ml_line_count);
+  wp->w_botline = MIN(wp->w_botline, wp->w_buffer->b_ml.ml_line_count + 1);
 
   check_topfill(wp, false);
 
@@ -1623,9 +1608,7 @@ void check_topfill(win_T *wp, bool down)
         wp->w_topfill = 0;
       } else {
         wp->w_topfill = wp->w_height_inner - n;
-        if (wp->w_topfill < 0) {
-          wp->w_topfill = 0;
-        }
+        wp->w_topfill = MAX(wp->w_topfill, 0);
       }
     }
   }
@@ -1849,15 +1832,11 @@ void scroll_cursor_top(win_T *wp, int min_scroll, int always)
     if (new_topline < wp->w_topline || always) {
       wp->w_topline = new_topline;
     }
-    if (wp->w_topline > wp->w_cursor.lnum) {
-      wp->w_topline = wp->w_cursor.lnum;
-    }
+    wp->w_topline = MIN(wp->w_topline, wp->w_cursor.lnum);
     wp->w_topfill = win_get_fill(wp, wp->w_topline);
     if (wp->w_topfill > 0 && extra > off) {
       wp->w_topfill -= extra - off;
-      if (wp->w_topfill < 0) {
-        wp->w_topfill = 0;
-      }
+      wp->w_topfill = MAX(wp->w_topfill, 0);
     }
     check_topfill(wp, false);
     if (wp->w_topline != old_topline) {
@@ -2276,18 +2255,14 @@ void cursor_correct(win_T *wp)
   if (wp->w_topline == 1) {
     above_wanted = 0;
     int max_off = wp->w_height_inner / 2;
-    if (below_wanted > max_off) {
-      below_wanted = max_off;
-    }
+    below_wanted = MIN(below_wanted, max_off);
   }
   validate_botline(wp);
   if (wp->w_botline == wp->w_buffer->b_ml.ml_line_count + 1
       && mouse_dragging == 0) {
     below_wanted = 0;
     int max_off = (wp->w_height_inner - 1) / 2;
-    if (above_wanted > max_off) {
-      above_wanted = max_off;
-    }
+    above_wanted = MIN(above_wanted, max_off);
   }
 
   // If there are sufficient file-lines above and below the cursor, we can