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;

```

src/nvim/textobject.c

@@ -1269,11 +1269,7 @@ int current_par(oparg_T *oap, int count, bool include, int type)
   // When visual area is more than one line: extend it.
   if (VIsual_active && start_lnum != VIsual.lnum) {
 extend:
-    if (start_lnum < VIsual.lnum) {
-      dir = BACKWARD;
-    } else {
-      dir = FORWARD;
-    }
+    dir = start_lnum < VIsual.lnum ? BACKWARD : FORWARD;
     for (int i = count; --i >= 0;) {
       if (start_lnum ==
           (dir == BACKWARD ? 1 : curbuf->b_ml.ml_line_count)) {