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/hashtab.c

@@ -316,10 +316,7 @@ static void hash_may_resize(hashtab_T *ht, size_t minitems)
     }
   } else {
     // Use specified size.
-    if (minitems < ht->ht_used) {
-      // just in case...
-      minitems = ht->ht_used;
-    }
+    minitems = MAX(minitems, ht->ht_used);
     // array is up to 2/3 full
     minsize = minitems * 3 / 2;
   }