tree-wide: drop spurious newlines (#8764)

Double newlines (i.e. one empty lines) are great to structure code. But
let's avoid triple newlines (i.e. two empty lines), quadruple newlines,
quintuple newlines, …, that's just spurious whitespace.

It's an easy way to drop 121 lines of code, and keeps the coding style
of our sources a bit tigther.

src/basic/socket-util.c

@@ -664,7 +664,6 @@ int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_
                 return -EOPNOTSUPP;
         }
 
-
         *ret = p;
         return 0;
 }
@@ -1127,7 +1126,6 @@ int flush_accept(int fd) {
         };
         int r;
 
-
         /* Similar to flush_fd() but flushes all incoming connection by accepting them and immediately closing them. */
 
         for (;;) {