According to https://mandoc.bsd.lv/mdoc/style/function_pointers.html.
before:
```
SYNOPSIS
#include <sys/types.h>
#include <sys/sbuf.h>
typedef int (
sbuf_drain_func) (
void *arg, const char *data, int len);
...
```
after:
```
SYNOPSIS
#include <sys/types.h>
#include <sys/sbuf.h>
typedef int
(*sbuf_drain_func)(void *arg, const char *data, int len);
...
```